Upgrade to eslint v7 (#5)

Update to eslint v7.
Update dependencies to latest releases.
Add release information to README.
Update test snapshots.

Author: zachintosh

README.md

@@ -74,3 +74,19 @@ If there has been a change (say you added a new rule, or there is a new valid vi
 - Because this is a public repository, there are complications in adding references to private services and communications channels, so there is no Travis CI build and no Code Climate integration.
 - Coverage reporting ends up reporting on `lint-output.js`, instead of `index.js`, and so is also not used.
 - As noted in the `Testing/Updating` section, the only validation we do is to run linting against a file with a set of known failures. So we make sure to run `npm test` via a pre-push hook.
+
+## Changelog:
+
+<details>
+<summary>Version 3 - ESLint 7</summary>
+
+- ESLint and dependencies updated to version 7.
+
+</details>
+
+<details>
+<summary>Version 2 - ESLint 6</summary>
+
+- ESLint and dependencies based on version 6.
+
+</details>

demo/test/snapshots/lint-output.js.md

@@ -9,11 +9,6 @@ Generated by [AVA](https://ava.li).
 > Snapshot 1
 
     `␊
-    example.test.html␊
-       5:12  error    describe.only not permitted  no-only-tests/no-only-tests␊
-       6:8   error    it.only not permitted        no-only-tests/no-only-tests␊
-      10:8   warning  it.skip not permitted        no-skip-tests/no-skip-tests␊
-    ␊
     example.js␊
        6:0   warning  Inline eslint-disable found                                                                                                    bestpractices/no-eslint-disable␊
        8:1   warning  Unexpected 'FIXME' comment                                                                                                     no-warning-comments␊
@@ -42,8 +37,8 @@ Generated by [AVA](https://ava.li).
       43:5   warning  'variable' is never reassigned. Use 'const' instead                                                                            prefer-const␊
       43:5   error    'variable' is assigned a value but never used                                                                                  no-unused-vars␊
       43:16  warning  This conditional operation returns the same value whether the condition is "true" or "false"                                   sonarjs/no-all-duplicated-branches␊
+      43:16  error    Unnecessary use of boolean literals in conditional expression                                                                  no-unneeded-ternary␊
       43:17  error    Unexpected constant condition                                                                                                  no-constant-condition␊
-      43:25  error    Unnecessary use of boolean literals in conditional expression                                                                  no-unneeded-ternary␊
       45:5   warning  Correct one of the identical sub-expressions on both sides of operator "&&"                                                    sonarjs/no-identical-expressions␊
       45:16  warning  Unexpected use of undefined                                                                                                    no-undefined␊
       45:40  warning  Unexpected use of undefined                                                                                                    no-undefined␊
@@ -57,9 +52,6 @@ Generated by [AVA](https://ava.li).
       51:3   error    '$' is not defined                                                                                                             no-undef␊
       52:3   error    Unexpected 'debugger' statement                                                                                                no-debugger␊
     ␊
-    /Users/clif/sandbox/frontier/common/eslint-config-tree/index.js␊
-      52:0  warning  Invalid JSDoc tag name "note"  jsdoc/check-tag-names␊
-    ␊
     example.json␊
       4:6   error  Property keys must be doublequoted  json/undefined␊
       4:14  error  Value expected                      json/value-expected␊
@@ -69,6 +61,14 @@ Generated by [AVA](https://ava.li).
       6:20  error  Trailing comma                      json/trailing-comma␊
       8:3   error  End of file expected                json/undefined␊
     ␊
+    example.test.html␊
+       5:12  error    describe.only not permitted  no-only-tests/no-only-tests␊
+       6:8   error    it.only not permitted        no-only-tests/no-only-tests␊
+      10:8   warning  it.skip not permitted        no-skip-tests/no-skip-tests␊
+    ␊
+    /Users/Xacheiree/dev/familysearch/tree/eslint-config-tree/index.js␊
+      52:0  warning  Invalid JSDoc tag name "note"  jsdoc/check-tag-names␊
+    ␊
     ✖ 52 problems (24 errors, 28 warnings)␊
       4 errors and 3 warnings potentially fixable with the `--fix` option.␊
     `

demo/test/snapshots/lint-output.js.snap

@@ -1,6 +1,6 @@
 {
   "name": "eslint-config-tree",
-  "version": "2.1.1",
+  "version": "3.0.0",
   "description": "Shared Tree configuration that contains overrides and enhancements on top of the base frontier configuration.",
   "main": "index.js",
   "repository": {
@@ -23,18 +23,18 @@
   },
   "dependencies": {
     "babel-eslint": "^8",
-    "eslint": "^6",
-    "eslint-config-standard-react": "^7",
+    "eslint": "^7",
     "eslint-config-standard": "^14",
+    "eslint-config-standard-react": "^9",
     "eslint-plugin-bestpractices": "git+https://github.com/skye2k2/eslint-plugin-bestpractices.git",
     "eslint-plugin-deprecate": "^0.5",
-    "eslint-plugin-html": "^6",
+    "eslint-plugin-html": "^6.0.3",
     "eslint-plugin-import": "^2",
-    "eslint-plugin-jsdoc": "^29",
-    "eslint-plugin-json": "^2",
+    "eslint-plugin-jsdoc": "^30",
+    "eslint-plugin-json": "^2.1.2",
     "eslint-plugin-no-only-tests": "^2",
     "eslint-plugin-no-skip-tests": "^1",
-    "eslint-plugin-node": "^9",
+    "eslint-plugin-node": "^11",
     "eslint-plugin-promise": "^4",
     "eslint-plugin-sonarjs": "^0.5",
     "eslint-plugin-standard": "^4",