Add 'static' because it is now required by NUnit 3.0.

StackExchange.Redis.Tests/Locking.cs

@@ -127,7 +127,7 @@ public enum TestMode
             NoMultiExec,
             Twemproxy
         }
-        public IEnumerable<TestMode> TestModes()
+        public static IEnumerable<TestMode> TestModes()
         {
             return (TestMode[])Enum.GetValues(typeof(TestMode));
         }