update older perl versions to use buster images

Author: haarg

.github/workflows/testsuite.yml

@@ -57,8 +57,8 @@ jobs:
             "5.30",
             "5.28",
             "5.26",
-            "5.24",
-            "5.22",
+            "5.24-buster",
+            "5.22-buster",
             "5.20-buster",
             "5.18-buster",
             "5.16-buster",