Housekeeping (#2520)

* enhance(project): Add .prettierrc to project
* chore(deps): Bump dependencies
* chore(view): Improve readability of the search form view
* chore(admin): Improve language used in the customize_register filter docblock
* chore(lint): Lint project assets
* chore(change-log): Improve/prepare the changelog for actual release
* chore(readme): Improve README feature list
* chore(readme): Update README theme directory structure
* chore(readme): Add GitHub sponsors badge
* chore(readme): Clean up various wording
* fix(ci): Fix failing tests
* fix(mix): Add index.php to purgecss scope (Supersedes #2423) (Credit @oxyc)

.circleci/config.yml

@@ -14,10 +14,10 @@ workflows:
             - run: yarn run build:production
           matrix:
             parameters:
-              version: ["10.21", "12.18", "14.4"]
+              version: ['12.18', '14.4']
       - php/test:
           name: php-<< matrix.version >>
           test-command: lint
           matrix:
             parameters:
-              version: ["7.2", "7.3", "7.4"]
+              version: ['7.2', '7.3', '7.4']