ci: run phpunit tests

Author: tsantos8080

.github/workflows/ci.yaml

@@ -0,0 +1,37 @@
+name: CI - Continuous Integration
+on:
+    pull_request:
+        types: [ opened, ready_for_review, synchronize, reopened ]
+jobs:
+    phpunit:
+        name: PHPUnit
+        runs-on: ubuntu-latest
+
+        strategy:
+            fail-fast: false
+            matrix:
+                php-version:
+                    - "7.4"
+                    - "8.0"
+                    - "8.1"
+                dependency-versions:
+                    - "lowest"
+                    - "highest"
+
+        steps:
+            -   name: Checkout
+                uses: actions/checkout@v3
+
+            -   name: Setup PHP
+                uses: shivammathur/setup-php@v2
+                with:
+                    php-version: ${{ matrix.php-version }}
+                    coverage: none
+
+            -   name: Install composer dependencies
+                uses: ramsey/composer-install@v2
+                with:
+                    dependency-versions: ${{ matrix.dependency-versions }}
+
+            -   name: Run PHPUnit
+                run: vendor/bin/phpunit tests