Demote Xcode select error to warning

Summary: This is firing regularly when people have a broken local setup.

Reviewed By: lawrencelomax

Differential Revision: D43834469

fbshipit-source-id: 1fbc2cf52f93046984e9846f8aed931106542b03

desktop/flipper-server-core/src/devices/ios/iOSDeviceManager.tsx

@@ -220,7 +220,8 @@ export class IOSDeviceManager {
         description: errorMessage,
       });
     } catch (e) {
-      console.error('Failed to determine Xcode version:', e);
+      // This is not an error. It depends on the user's local setup that we cannot influence.
+      console.warn('Failed to determine Xcode version:', e);
     }
   }
 }