Add support for PHP 8.1

.github/workflows/continuous-integration.yml

@@ -66,6 +66,7 @@ jobs:
           - "7.3"
           - "7.4"
           - "8.0"
+          - "8.1"
 
     steps:
       - name: "Checkout repository"
@@ -114,7 +115,6 @@ jobs:
   unit-tests:
     name: "Unit Tests"
     runs-on: "ubuntu-latest"
-    continue-on-error: ${{ matrix.experimental }}
 
     strategy:
       fail-fast: false
@@ -124,11 +124,8 @@ jobs:
           - "7.3"
           - "7.4"
           - "8.0"
-        experimental:
-          - false
         include:
           - php-version: "8.1"
-            experimental: true
             composer-options: "--ignore-platform-req=php"
 
     steps: