Fix AskTimeoutException message formatting bug (#7350)

Co-authored-by: Aaron Stannard <aaron@petabridge.com>

Author: Arkatufus

src/core/Akka.Tests/Actor/AskSpec.cs

@@ -218,7 +218,7 @@ public async Task Ask_should_honor_config_specified_timeout()
             }
             catch (AskTimeoutException e)
             {
-                Assert.Equal("Timeout after 00:00:03 seconds", e.Message);
+                Assert.Equal("Timeout after 3.00 seconds", e.Message);
             }
         }
 

src/core/Akka/Actor/Futures.cs

@@ -137,7 +137,7 @@ public static Task<T> Ask<T>(this ICanTell self, Func<IActorRef, object> message
 
                 ctr1 = timeoutCancellation.Token.Register(() =>
                 {
-                    result.TrySetException(new AskTimeoutException($"Timeout after {timeout} seconds"));
+                    result.TrySetException(new AskTimeoutException($"Timeout after {timeout.Value.TotalSeconds:F2} seconds"));
                 });
 
                 timeoutCancellation.CancelAfter(timeout.Value);