ci: add continuous integration workflow

Author: carlalexander

.github/workflows/ci.yml

@@ -0,0 +1,49 @@
+name: Continuous Integration
+on:
+  push:
+    branches-ignore:
+      - 'release-please**'
+  pull_request:
+    branches-ignore:
+      - 'release-please**'
+
+jobs:
+  code-quality:
+    name: Run code quality checks on PHP 8.0
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.0'
+      - name: Install dependencies
+        run: composer update --no-ansi --no-interaction --no-scripts --prefer-dist
+      - name: Run code quality checks
+        run: vendor/bin/grumphp run --testsuite=code_quality
+  php-tests:
+    name: Run tests on ${{ matrix.php }}${{ matrix.dependency-version != '' && ' (--prefer-lowest)' || '' }}
+    needs: code-quality
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        dependency-version: ['']
+        php: ['7.4', '8.0', '8.1', '8.2', '8.3', '8.4']
+        include:
+          - dependency-version: '--prefer-lowest'
+            php: '7.4'
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - name: Setup PHP ${{ matrix.php }}
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+      - name: Remove GrumPHP
+        run: composer remove --dev phpro/grumphp
+      - name: Install dependencies
+        run: composer update ${{ matrix.dependency-version }} --no-ansi --no-interaction --no-scripts --prefer-dist
+      - name: Run unit tests
+        run: vendor/bin/phpunit