Update tests to only run on 8.4.

Author: BusterNeece

.github/workflows/testsuite.yml

@@ -8,7 +8,7 @@ jobs :
 
     strategy :
       matrix :
-        php-version : [ '8.2', '8.3', '8.4' ]
+        php-version : [ '8.4' ]
     steps :
       - uses : actions/checkout@v1