Add GitHub actions configuration

.github/workflows/test.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches: [ develop ]
+  pull_request:
+    branches: [ develop ]
+
+jobs:
+  build:
+
+    runs-on: ${{ matrix.operating-system }}
+    strategy:
+      matrix:
+        operating-system: [ubuntu-latest]
+        php-versions: ['7.4', '8.0']
+
+    name: PHP ${{ matrix.php-versions }} Test on ${{ matrix.operating-system }}
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+          extensions: mbstring, intl
+          ini-values: post_max_size=256M, short_open_tag=On
+          coverage: xdebug
+
+      - name: Validate composer.json
+        run: composer validate --strict
+
+      - name: Install dependencies
+        run: composer install --prefer-dist --no-progress --no-suggest
+
+#      TODO: Add codestyle checks
+
+#      TODO: Add unit tests