fix: worker hangs sometimes

[Sobes76rus]

issues: #63 #81

child process inherits signal handlers from parent

the problem is that the terminate signal was triggered before the signal handler of the child process was set, we must set it immediately after the process starts

and I suggest telling the parent process that the worker is ready before the parent continues with the event queue.
or at least wait a while for the worker process to set the signal handler
or we can handle it in parent signal handler, and raise an error if it is not a main process

[s3rius]

Actually good suggestions. Can you implement these?

I would implement it using multiprocessing Queue. Since we know how many workers we would like to have, so we can just wait for n messages from this queue, where n is the number of worker processes.

[codecov-commenter]

Codecov Report

Merging #162 (dc9acb6) into develop (e66f3aa) will increase coverage by 2.44%.
The diff coverage is 76.47%.

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@@             Coverage Diff             @@
##           develop     #162      +/-   ##
===========================================
+ Coverage    67.62%   70.06%   +2.44%     
===========================================
  Files           37       42       +5     
  Lines          942     1313     +371     
===========================================
+ Hits           637      920     +283     
- Misses         305      393      +88     

Impacted Files	Coverage Δ
taskiq/abc/middleware.py	100.00% <ø> (ø)
taskiq/abc/result_backend.py	100.00% <ø> (ø)
taskiq/cli/scheduler/run.py	0.00% <0.00%> (ø)
taskiq/cli/watcher.py	0.00% <ø> (ø)
taskiq/cli/worker/log_collector.py	100.00% <ø> (ø)
taskiq/cli/worker/process_manager.py	0.00% <0.00%> (ø)
taskiq/cli/worker/run.py	0.00% <0.00%> (ø)
taskiq/events.py	100.00% <ø> (ø)
taskiq/receiver/params_parser.py	96.87% <ø> (ø)
taskiq/result_backends/dummy.py	100.00% <ø> (ø)
... and 23 more

... and 1 file with indirect coverage changes

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[Sobes76rus]

OK, I did it through multiprocess.Event.

[s3rius]

I think it's great. Thank you.