Move to GitHub actions (#213)

* Move from travis to github actions

* Remove 7.1 and 7.2 from github actions ci

* Add php 8.1 to CI

Author: mbonneau

.github/workflows/ci.yml

@@ -0,0 +1,29 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  PHPUnit:
+    name: PHPUnit (PHP ${{ matrix.php }} on ${{ matrix.os }})
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os:
+          - ubuntu-20.04
+          - windows-2019
+        php:
+          - 8.1
+          - 8.0
+          - 7.4
+          - 7.3
+          - 7.2
+    steps:
+      - uses: actions/checkout@v2
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: xdebug
+      - run: composer install
+      - run: vendor/bin/phpunit --coverage-text