Tests: Time(): standardize format to include ms

StackExchange.Redis.Tests/BasicOps.cs

@@ -284,7 +284,6 @@ public void GetWithExpiryWrongTypeSync()
         [Fact]
         public async Task TestQuit()
         {
-            string Time() => DateTime.UtcNow.ToString("HH:mm:ss.fff");
             SetExpectedAmbientFailureCount(1);
             using (var muxer = Create(allowAdmin: true))
             {

StackExchange.Redis.Tests/Helpers/TextWriterOutputHelper.cs

@@ -17,7 +17,7 @@ public override void WriteLine(string value)
         {
             try
             {
-                base.Write(DateTime.UtcNow.ToString("HH:mm:ss.fff"));
+                base.Write(TestBase.Time());
                 base.Write(": ");
                 base.WriteLine(value);
             }

StackExchange.Redis.Tests/TestBase.cs

@@ -83,7 +83,7 @@ static TestBase()
                 }
             };
         }
-        private string Time() => DateTime.UtcNow.ToString("T");
+        internal static string Time() => DateTime.UtcNow.ToString("HH:mm:ss.fff");
         protected void OnConnectionFailed(object sender, ConnectionFailedEventArgs e)
         {
             Interlocked.Increment(ref privateFailCount);