Added Github action to eventually replace Travis CI workflow

.github/php.yml

@@ -0,0 +1,38 @@
+name: Github Build
+on: [push, pull_request]
+jobs:
+    build:
+        runs-on: ubuntu-latest
+        strategy:
+            fail-fast: false
+            matrix:
+                php: ['7.4', '7.3', '7.2', '8.0', '8.1']
+        name: PHP ${{ matrix.php }}
+        steps:
+            - uses: actions/checkout@v1
+            - name: Install PHP
+              uses: shivammathur/setup-php@v2
+              with:
+                  php-version: ${{ matrix.php }}
+                  coverage: xdebug
+            - name: Report PHP version
+              run: php -v
+            - name: Validate composer.json and composer.lock
+              run: composer validate
+            - name: Get Composer Cache Directory
+              id: composer-cache
+              run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+            - name: Cache dependencies
+              uses: actions/cache@v1
+              with:
+                  path: ${{ steps.composer-cache.outputs.dir }}
+                  key: ${{ matrix.php }}-composer-${{ hashFiles('**/composer.lock') }}
+                  restore-keys: ${{ matrix.php }}-composer-
+            - name: Install dependencies
+              run: composer install --prefer-dist --no-progress --no-suggest
+            - name: Run PHPStan
+              run: composer phpstan
+            - name: Run PHP-CS
+              run: composer check-style
+            - name: Run test suite
+              run: vendor/bin/phpunit