Merge branch 'renovate/major-stylelint-and-related' into 'master'

Update dependency @gitlab/stylelint-config to v4

See merge request gitlab-org/gitlab!79507

package.json

@@ -207,7 +207,7 @@
   "devDependencies": {
     "@babel/plugin-transform-modules-commonjs": "^7.10.1",
     "@gitlab/eslint-plugin": "10.0.0",
-    "@gitlab/stylelint-config": "3.0.0",
+    "@gitlab/stylelint-config": "4.0.0",
     "@graphql-eslint/eslint-plugin": "3.0.0",
     "@testing-library/dom": "^7.16.2",
     "@vue/test-utils": "1.3.0",
@@ -246,7 +246,7 @@
     "miragejs": "^0.1.40",
     "mock-apollo-client": "^0.7.0",
     "nodemon": "^2.0.4",
-    "postcss": "^7.0.14",
+    "postcss": "^8.4.5",
     "prettier": "2.2.1",
     "prosemirror-schema-basic": "^1.1.2",
     "prosemirror-schema-list": "^1.1.6",
@@ -254,7 +254,7 @@
     "purgecss": "^4.0.3",
     "purgecss-from-html": "^4.0.3",
     "sass": "^1.32.12",
-    "stylelint": "13.9.0",
+    "stylelint": "^14.3.0",
     "timezone-mock": "^1.0.8",
     "vue-jest": "4.0.1",
     "webpack-dev-server": "^3.11.3",