Update ci.yml to include other PHP versions

Author: adamtomat

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
         runs-on: ubuntu-latest
         strategy:
             matrix:
-                php_version: [8.4]
+                php_version: [8.1, 8.2, 8.3, 8.4]
                 composer_flags: ["", "--prefer-lowest"]
 
         steps: