Increase wxWebRequest tests timeout

10s seems to often be not long enough for the Travis/AppVeyor machines.

tests/net/webrequest.cpp

@@ -111,7 +111,7 @@ public:
 
     void RunLoopWithTimeout()
     {
-        StartOnce(10000); // Ensure that we exit the loop after 10s.
+        StartOnce(30000); // Ensure that we exit the loop after 30s.
         loop.Run();
         Stop();
     }