Enable Github Actions for unit testing

.github/workflows/run-tests.yml

@@ -0,0 +1,41 @@
+name: PHPUnit tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Validate composer.json and composer.lock
+      run: composer validate --strict
+
+    - name: Cache Composer packages
+      id: composer-cache
+      uses: actions/cache@v3
+      with:
+        path: vendor
+        key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-php-
+
+    - name: Install dependencies
+      run: composer install --prefer-dist --no-progress
+
+    - name: Setup ElasticSearch
+      uses: getong/elasticsearch-action@v1.2
+      with:
+        elasticsearch version: 7.17.1
+
+    - name: Run test suite
+      run: ./vendor/bin/phpunit