Add assertion that actual heartbeat timeout has been updated with the server value.

Author: lukebakken

projects/Test/Integration/GH/TestGitHubIssues.cs

@@ -128,6 +128,8 @@ public async Task TestHeartbeatTimeoutValue_GH1756()
             };
 
             _conn = await connectionFactory.CreateConnectionAsync("some-name");
+
+            Assert.True(_conn.Heartbeat != default);
         }
     }
 }