Added test cases about php 8.1

Author: limingxinleo

.github/workflows/test.yml

@@ -32,7 +32,7 @@ jobs:
     strategy:
       matrix:
         os: [ ubuntu-latest ]
-        php-version: [ '8.0' ]
+        php-version: [ '8.0', '8.1' ]
         swoole-version: [ 'v5.0.0', 'master' ]
       max-parallel: 5
     env: