ci: fix copy-paste mistake in 16eb823.

Reported-By: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20220213024704.GN31460@telsasoft.com

Author: anarazel

.cirrus.yml

@@ -32,7 +32,7 @@ on_failure: &on_failure
   log_artifacts:
     paths:
       - "**/*.log"
-      - "**/.diffs"
+      - "**/*.diffs"
       - "**/regress_log_*"
     type: text/plain