TECH-2964 - Bumping Python to 3.9

[OleksandrUA]

Python 3.10 doesn't work due to next Exception

Traceback (most recent call last):
  File "/usr/local/lib/python3.10/site-packages/pytz/lazy.py", line 3, in <module>
    from UserDict import DictMixin
ModuleNotFoundError: No module named 'UserDict'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.10/runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/local/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/opt/keeper/chief-keeper/chief_keeper/chief_keeper.py", line 34, in <module>
    from pymaker.lifecycle import Lifecycle
  File "/opt/keeper/chief-keeper/lib/pymaker/pymaker/lifecycle.py", line 24, in <module>
    import pytz
  File "/usr/local/lib/python3.10/site-packages/pytz/__init__.py", line 32, in <module>
    from pytz.lazy import LazyDict, LazyList, LazySet
  File "/usr/local/lib/python3.10/site-packages/pytz/lazy.py", line 5, in <module>
    from collections import Mapping as DictMixin
ImportError: cannot import name 'Mapping' from 'collections' (/usr/local/lib/python3.10/collections/__init__.py)