chore: fix multithreading log test not being able to pickle local worker function (#423)

This PR is fixing failing unit test `test_multi_process` when running
`poetry run pytest tests/unit`.

```
tests/unit/test_log.py:119: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/usr/local/Cellar/python@3.9/3.9.18/Frameworks/Python.framework/Versions/3.9/lib/python3.9/multiprocessing/process.py:121: in start
    self._popen = self._Popen(self)
/usr/local/Cellar/python@3.9/3.9.18/Frameworks/Python.framework/Versions/3.9/lib/python3.9/multiprocessing/context.py:224: in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
/usr/local/Cellar/python@3.9/3.9.18/Frameworks/Python.framework/Versions/3.9/lib/python3.9/multiprocessing/context.py:284: in _Popen
    return Popen(process_obj)
/usr/local/Cellar/python@3.9/3.9.18/Frameworks/Python.framework/Versions/3.9/lib/python3.9/multiprocessing/popen_spawn_posix.py:32: in __init__
    super().__init__(process_obj)
/usr/local/Cellar/python@3.9/3.9.18/Frameworks/Python.framework/Versions/3.9/lib/python3.9/multiprocessing/popen_fork.py:19: in __init__
    self._launch(process_obj)
/usr/local/Cellar/python@3.9/3.9.18/Frameworks/Python.framework/Versions/3.9/lib/python3.9/multiprocessing/popen_spawn_posix.py:47: in _launch
    reduction.dump(process_obj, fp)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

obj = <Process name='Process-1' parent=76837 initial>, file = <_io.BytesIO object at 0x10fe45810>, protocol = None

    def dump(obj, file, protocol=None):
        '''Replacement for pickle.dump() using ForkingPickler.'''
>       ForkingPickler(file, protocol).dump(obj)
E       AttributeError: Can't pickle local object 'TestLogs.test_multi_process.<locals>.worker'

/usr/local/Cellar/python@3.9/3.9.18/Frameworks/Python.framework/Versions/3.9/lib/python3.9/multiprocessing/reduction.py:60: AttributeError

```

Author: dkvashninsplunk