Add github workflow.

Signed-off-by: Mior Muhammad Zaki <crynobone@gmail.com>

.github/workflows/tests.yml

@@ -0,0 +1,41 @@
+name: tests
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '0 0 * * *'
+
+jobs:
+  tests:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        php: [7.4, 7.3, 7.2]
+        os: [ubuntu-latest, windows-latest]
+
+    name: PHP${{ matrix.php }} on ${{ matrix.os }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v1
+
+      - name: Cache dependencies
+        uses: actions/cache@v1
+        with:
+          path: ~/.composer/cache/files
+          key: dependencies-php-${{ matrix.php }}-composer-${{ hashFiles('composer.json') }}
+
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v1
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: dom, curl, libxml, mbstring, zip, pcntl, pdo, sqlite, pdo_sqlite, mysql, mysqli, pdo_mysql, bcmath, soap, intl, gd, exif, iconv, imagick
+          coverage: none
+
+      - name: Install dependencies
+        run: |
+          composer update --prefer-stable --prefer-dist --no-interaction --no-suggest
+      - name: Execute tests
+        run: vendor/bin/phpunit