chore(deps): update dependency @sourcegraph/eslint-config to ^0.21.0

Author: renovate-bot

package.json

@@ -100,7 +100,7 @@
   "devDependencies": {
     "@commitlint/cli": "^11.0.0",
     "@commitlint/config-conventional": "^11.0.0",
-    "@sourcegraph/eslint-config": "^0.20.19",
+    "@sourcegraph/eslint-config": "^0.21.0",
     "@sourcegraph/prettierrc": "^3.0.3",
     "@sourcegraph/tsconfig": "^4.0.1",
     "@types/node": "12.12.14",

yarn.lock

@@ -481,10 +481,10 @@
     lodash "^4.17.4"
     read-pkg-up "^7.0.0"
 
-"@sourcegraph/eslint-config@^0.20.19":
-  version "0.20.19"
-  resolved "https://registry.yarnpkg.com/@sourcegraph/eslint-config/-/eslint-config-0.20.19.tgz#52e38a7db9596a0a0032880bac45c22d78737195"
-  integrity sha512-X9YVu89hPbEc2FjGQ5uVkmi6AhOA+XkCPiXXrEmLe1OVPt3G2d0wsugSpZj4yRdfzMBMZXezI+w7ayUVFJktDQ==
+"@sourcegraph/eslint-config@^0.21.0":
+  version "0.21.0"
+  resolved "https://registry.yarnpkg.com/@sourcegraph/eslint-config/-/eslint-config-0.21.0.tgz#9234a65193bb026c157dac5a0b95b115f3e2f324"
+  integrity sha512-3yynNBgvREtKXKLqEIsB/txg39e5X8ehOPE1zUVPRF9LDcaO1cbxbB48YgMyS0JHXTi6DkJnm5RRc+fUmFq29Q==
   dependencies:
     "@sourcegraph/prettierrc" "^3.0.3"
     "@typescript-eslint/eslint-plugin" "^4.9.1"