--profile doesn't work with Python 3.12+

[mistydemeo]

Python 3.12 introduced a new limitation preventing multiple nested profilers from running at the same time: python/cpython#110770

We're running into this limitation with warcprox. Attempting to run with --profile enabled will cause it to immediately error out with an Another profiling tool is already active exception the first time it tries to spin up a BasePostfetchProcessor thread.

We instantiate cProfiler profilers in one place - inside BasePostfetchProcessor.run:

warcprox/warcprox/__init__.py

Lines 106 to 109 in 37e4cd5

	self.profiler = cProfile.Profile()
	self.profiler.enable()
	self._run()
	self.profiler.disable()

We do, however, additionally interact with those profilers via PooledMitmProxy, where we grab the profiler from the thread, enable it, process the request, and disable it again:

warcprox/warcprox/mitmproxy.py

Lines 753 to 756 in f7dd1e7

	profiler = self.profilers[threading.current_thread().ident]
	profiler.enable()
	self._process_request_thread(request, client_address)
	profiler.disable()

This could either be repeated invocations to enable() the same profiler when it's already enabled (calling .enable() twice on the same profiler raises an exception), or a call to enable() a second profiler from a different thread while a profiler from the first thread is still active.