[gardening] Instead of iterating over a dictionary's (k,v) and just using the key, just iterate over the keys! NFC.

Author: gottesmm

utils/update-checkout

@@ -171,7 +171,7 @@ By default, updates your checkouts of Swift, SourceKit, LLDB, and SwiftPM.""")
             config, clone_with_ssh, branch, skip_history, args.skip_repository)
 
     repo_branch = branch
-    for dir_name, _ in config["repositories"].items():
+    for dir_name in config["repositories"].keys():
         if dir_name in args.skip_repository:
             print("--- Skipping '" + dir_name + "' ---")
             continue