Add GitHub action support

Add Github Actions to RTLCSS for PHP, using the recommended
configuration. Fixes #3.

Author: sarjona

.github/workflows/ci.yml

@@ -0,0 +1,29 @@
+name: RTLCSS for PHP CI
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-18.04
+
+    strategy:
+      fail-fast: false
+      matrix:
+        php: ['7.3', '7.4', '8.0']
+
+    steps:
+      - name: Check out repository code
+        uses: actions/checkout@v2
+
+      - name: Setup PHP ${{ matrix.php }}
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: none
+
+      - name: Run composer
+        uses: php-actions/composer@v6
+
+      - name: PHPUnit tests
+        run:
+          vendor/bin/phpunit

README.md

@@ -1,6 +1,8 @@
 RTLCSS for PHP
 --------------
 
+[![Codechecker CI](https://github.com/moodlehq/rtlcss-php/actions/workflows/ci.yml/badge.svg)](https://github.com/moodlehq/rtlcss-php/actions/workflows/ci.yml)
+
 RTLCSS is a framework for converting Left-To-Right (LTR) Cascading Style Sheets(CSS) to Right-To-Left (RTL).
 
 ## Usage