Expand test matrix for PHP 8.5 (#27)

Author: Firehed

.github/workflows/test.yml

@@ -23,7 +23,8 @@ jobs:
           - '8.1'
           - '8.2'
           - '8.3'
-          - '8.4-dev'
+          - '8.4'
+          - '8.5-dev'
 
     steps:
       - name: Check out code