migrate from travis to gh action

Signed-off-by: Matthew Peveler <matt.peveler@gmail.com>

.github/workflows/test.yml

@@ -0,0 +1,26 @@
+name: Test
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php-version: ['5.6', '7.0', '7.1', '7.2', '7.3', '7.4']
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: shivammathur/setup-php@v2
+      with:
+        php-version: ${{ matrix.php-version }}
+        tools: composer
+        coverage: xdebug
+
+    - uses: ramsey/composer-install@v1
+
+    - run: vendor/bin/phpunit --coverage-text tests