GitHub actions, normalization and support for PHP8

.github/workflows/php.yml

@@ -7,11 +7,27 @@ on:
     branches: [ master ]
 
 jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
+  run:
+    runs-on: ${{ matrix.operating-system }}
+    strategy:
+      matrix:
+        operating-system: ['ubuntu-latest', 'windows-latest', 'macos-latest']
+        php-versions: ['7.4', '8.0', '8.1']
+        phpunit-versions: ['latest']
+        include:
+          - operating-system: 'ubuntu-latest'
+            php-versions: '7.3'
+            phpunit-versions: '8.5.21'
     steps:
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+          extensions: mbstring, intl
+          ini-values: post_max_size=256M, max_execution_time=180
+          coverage: xdebug
+          tools: php-cs-fixer, phpunit:${{ matrix.phpunit-versions }}
+
     - uses: actions/checkout@v2
 
     - name: Validate composer.json and composer.lock
@@ -22,15 +38,13 @@ jobs:
       uses: actions/cache@v2
       with:
         path: vendor
-        key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
+        key: ${{ runner.os }}-php-${{ matrix.php-versions }}-${{ hashFiles('**/composer.lock') }}
         restore-keys: |
+          ${{ runner.os }}-php-${{ matrix.php-versions }}-
           ${{ runner.os }}-php-
 
     - name: Install dependencies
       run: composer install --prefer-dist --no-progress
 
-    # Add a test script to composer.json, for instance: "test": "vendor/bin/phpunit"
-    # Docs: https://getcomposer.org/doc/articles/scripts.md
-
     - name: Run test suite
-      run: vendor/bin/phpunit
+      run: composer test