ci: Update PR title formatting for Squash and Merge (#711)

Changed the PR reference format from (`#123`) to (PR-123) in squash commit messages
to prevent GitHub from automatically adding reference comments to PRs when
`master-dev-c3-new` is force pushed.

release/ci/squash_and_merge_prs.py

@@ -147,7 +147,7 @@ def process_pr(pr_data, source_branch, target_branch, squash_script_path):
           squash_script_path,
           '--target', target_branch,
           '--source', branch,
-          '--title', f"{title} (#{pr_number})",
+          '--title', f"{title} (PR-{pr_number})",
         ], check=True)
 
         print(f"Successfully processed PR #{pr_number}")