GC test only "good" in release

StackExchange.Redis.Tests/GarbageCollectionTests.cs

@@ -22,6 +22,9 @@ private static void ForceGC()
         [Fact]
         public void MuxerIsCollected()
         {
+#if DEBUG
+            Skip.Inconclusive("Only predictable in builds");
+#endif
             // this is more nuanced than it looks; multiple sockets with
             // async callbacks, plus a heartbeat on a timer