Update pull_request.yml

There is no 6.1-noble in Ba Sing Se.

Author: grynspan

.github/workflows/pull_request.yml

@@ -27,4 +27,4 @@ jobs:
       docs_check_enabled: false
       unacceptable_language_check_enabled: false
       format_check_enabled: false
-      api_breakage_check_container_image: swift:6.2-noble
+      api_breakage_check_container_image: swift:nightly-main-jammy