Update RCTDevMenu.mm (#35910)

Summary:
Fixed typo with the word "running" in 2 places when failing to open Flipper.

Fixes https://github.com/facebook/react-native/issues/35899 .

Changelog:
[Internal] [Changed] - Fix typo with the word "running" when failing to open Flipper

Pull Request resolved: https://github.com/facebook/react-native/pull/35910

Reviewed By: christophpurrer

Differential Revision: D42641042

Pulled By: sshic

fbshipit-source-id: acebb26ab921e98235c4f8e8535fa89be2ffa8cd

React/CoreModules/RCTDevMenu.mm

@@ -271,7 +271,7 @@ RCT_EXPORT_MODULE()
                              [RCTInspectorDevServerHelper
                                           openURL:@"flipper://null/Hermesdebuggerrn?device=React%20Native"
                                     withBundleURL:bundleManager.bundleURL
-                                 withErrorMessage:@"Failed to open Flipper. Please check that Metro is runnning."];
+                                 withErrorMessage:@"Failed to open Flipper. Please check that Metro is running."];
                            }]];
 
       [items addObject:[RCTDevMenuItem
@@ -282,7 +282,7 @@ RCT_EXPORT_MODULE()
                              [RCTInspectorDevServerHelper
                                           openURL:@"flipper://null/React?device=React%20Native"
                                     withBundleURL:bundleManager.bundleURL
-                                 withErrorMessage:@"Failed to open Flipper. Please check that Metro is runnning."];
+                                 withErrorMessage:@"Failed to open Flipper. Please check that Metro is running."];
                            }]];
     } else if (devSettings.isRemoteDebuggingAvailable) {
 #else