Try to fix flaky test (#330)

We'll start by more than doubling the time we allocate for this test to
run, since the filesystem on a GitHub Actions runner appears slow. If
that isn't enough to fix it, we should remove the test entirely.

src/LibChorusTests/notes/AnnotationRepositoryTests.cs

@@ -227,8 +227,8 @@ public void AddAnnotation_NotifiesIndices()
 		[Platform(Exclude = "Win", Reason = "flaky (on both platforms)")]
 		public void ExternalFileModification_NotifiesIndices_ButSaveDoesNot()
 		{
-			const int SleepTime = 10; // milliseconds
-			const int MaxTries = 1000; // max try 10ms * 1000 = 10s
+			const int SleepTime = 25; // milliseconds
+			const int MaxTries = 1000; // max try 25ms * 1000 = 25s
 			using (var t = new TempFile(@"<notes version='0'><annotation guid='123'>
 <message guid='234'>&lt;p&gt;hello</message></annotation></notes>"))
 			{