Resolves #16. Split repository and move all custom fixers to separate repository

.github/workflows/ci.yml

@@ -49,10 +49,3 @@ jobs:
       - name: PHP-CS-Fixer
         if: matrix.php-versions == '8.1'
         run: vendor/bin/php-cs-fixer fix --dry-run --format=checkstyle | cs2pr
-
-      # https://github.com/marketplace/actions/setup-php-action#phpunit
-      - name: Setup problem matchers for PHPUnit
-        run: echo "::add-matcher::${{ runner.tool_cache }}/phpunit.json"
-
-      - name: PHPUnit
-        run: vendor/bin/phpunit