fix test_request_timeout on Windows

Mainly, tests fail with 

    self.triggers.popleft()()
    IndexError: pop from an empty deque

But sometimes I have also seen an assertion error when `response.request_time` is smaller than 0.099
self.triggers shouldn't be empty; if it is it means the test isn't really testing what it is supposed to. This probably means we need to increase the request_timeout (along with the allowed range in the assertion). The request_timeout should be long enough to allow the request to be issued and reach the trigger point.