Migrate travis-ci to github action

Author: janlam7

.gitattributes

@@ -0,0 +1,5 @@
+.gitattributes export-ignore
+.github export-ignore
+.gitignore export-ignore
+/test export-ignore
+/phpunit.xml.dist export-ignore

.github/workflows/main.yaml

@@ -0,0 +1,35 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php-versions: ['7.3', '7.4']
+    name: PHP ${{ matrix.php-versions }}
+    steps:
+      -   uses: actions/checkout@v2
+      -   uses: shivammathur/setup-php@v2
+          with:
+            php-version: ${{ matrix.php-versions }}
+      -   name: Get composer cache directory
+          id: composer-cache
+          run: echo "::set-output name=dir::$(composer config cache-files-dir)"
+      -   uses: actions/cache@v2
+          with:
+            path: ${{ steps.composer-cache.outputs.dir }}
+            key: ${{ runner.os }}-composer-${{ hashFiles('**/composer.lock') }}
+            restore-keys: ${{ runner.os }}-composer-
+      -   name: composer install
+          run: composer install --no-progress --prefer-dist --optimize-autoloader
+      -   name: phpunit
+          run: php vendor/bin/phpunit
+      -   name: phpcs
+          run: php vendor/bin/phpcs