PHPCS 4.x | GH Actions: fix test workflow for PHP nightly

Not all PHPUnit dependencies allow for PHP 8.1/nightly yet, so `composer install` with the `--ignore-platform-reqs` options to allow to run the tests anyway.

Author: jrfnl

.github/workflows/test.yml

@@ -67,9 +67,17 @@ jobs:
 
       # Install dependencies and handle caching in one go.
       # @link https://github.com/marketplace/actions/install-composer-dependencies
-      - name: Install Composer dependencies
+      - name: Install Composer dependencies - normal
+        if: ${{ matrix.experimental == false }}
         uses: "ramsey/composer-install@v1"
 
+      # For PHP nightly, install with ignore platform reqs as not all PHPUnit allow for it yet.
+      - name: Install Composer dependencies - with ignore platform
+        if: ${{ matrix.experimental == true }}
+        uses: "ramsey/composer-install@v1"
+        with:
+          composer-options: --ignore-platform-reqs
+
       # Note: The code style check is run multiple times against every PHP version
       # as it also acts as an integration test.
       - name: 'PHPCS: set the path to PHP'