Upgrade dev dependencies

- These have breaking changes, but nothing that affects the published build.
- fix CSS imports to meet new stylelint standard
- fix jest config to move `collectCoverageFrom` to top level

examples/index.css

@@ -1,4 +1,4 @@
-@import '~purecss/build/base.css';
+@import url('~purecss/build/base.css');
 
 :root {
 	--border-style: 1px solid #e8e8e8;

examples/util/example.css

@@ -1,4 +1,4 @@
-@import '~purecss/build/base.css';
+@import url('~purecss/build/base.css');
 
 body {
 	position: absolute;

jest.config.json

@@ -8,19 +8,19 @@
 		"text",
 		"text-summary"
 	],
+	"collectCoverageFrom": [
+		"src/**/*.{js,ts}",
+		"!src/index.{js,ts}",
+		"!src/browser.{js,ts}",
+		"!**/tests/**"
+	],
 	"projects": [
 		{
 			"displayName": "test",
 			"clearMocks": true,
 			"roots": [
 				"<rootDir>/src"
 			],
-			"collectCoverageFrom": [
-				"src/**/*.{js,ts}",
-				"!src/index.{js,ts}",
-				"!src/browser.{js,ts}",
-				"!**/tests/**"
-			],
 			"testMatch": [
 				"<rootDir>/src/**/__tests__/**/*.{js,ts}",
 				"<rootDir>/src/**/*.{spec,test}.{js,ts}"