Python prompt tests count requests that other local processes send to the capture server #114

sdks/python/tests/test_prompts.py::test_concurrent_calls_share_one_fetch and test_get_prompt_keeps_a_prompt_for_the_ttl_then_refreshes_it_in_the_background fail intermittently on a busy macOS machine ('assert 2 == 1', 'assert 3 == 2'). The failures also occur without the last commits of the fix of #97 (#112). The extra captured request has the headers 'user-agent': 'node' and 'sec-fetch-mode': 'cors', so a Node process, not get_prompt (urllib), sends it to the ephemeral port of the CaptureServer.

Make the tests count only their own requests, for example by the authorization header or by a path with a random part, so that a different local process cannot change the count. Then run the file 20 times in a loop and expect no failure.