Test on PHP 8.2

With PHP 8.2 coming out later this year, we should be reading for it's release to ensure all out code works on it.

Refs: reactphp/event-loop#258

.github/workflows/ci.yml

@@ -11,6 +11,7 @@ jobs:
     strategy:
       matrix:
         php:
+          - 8.2
           - 8.1
     steps:
       - uses: actions/checkout@v2