Fix swift-format branch in the 5.3 scheme

Author: MaxDesiatov

utils/update_checkout/update-checkout-config.json

@@ -97,7 +97,7 @@
                 "cmake": "v3.16.5",               
                 "indexstore-db": "release/5.3",
                 "sourcekit-lsp": "release/5.3",
-                "swift-format": "master"
+                "swift-format": "main"
             }
         },
         "master": {