Found a flaky test #631

I run into a flaky test https://github.com/gitx/gitx/actions/runs/34750376507/job/103705883239?pr=625

/Users/runner/work/gitx/gitx/GitXTests/PBGitIndexRefreshTests.m:178: error: -[PBGitIndexRefreshTests testACommandResultDoesNotAnnounceAnIndexUpdate] : Asynchronous wait failed: Exceeded timeout of 1 seconds, with unfulfilled expectations: "Expect notification 'PBGitIndexIndexRefreshStatus' from <PBRecordingIndex: 0xb65f33f00>".

It's a flaky CI timing issue: postIndexRefreshSuccess: posts via dispatch_async(main queue, …), and the test's waitForExpectations:timeout:1.0 is tight on a loaded CI runner