Remove experimental for PHP 8.1 on CI

Author: ruudk

.github/workflows/build-and-test.yml

@@ -7,11 +7,8 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['7.0', '7.1', '7.2', '7.3', '7.4', '8.0']
+        php: ['7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1']
         experimental: [false]
-        include:
-          - php: '8.1'
-            experimental: true
     steps:
       - name: Checkout
         uses: actions/checkout@v2