Several updates in code

[C3EQUALZz]

• Rewrote a few tests using pytest. Removed code duplication in some tests.
• Removed your gcd implementation and replaced it with math.gcd from the Python standard library for better performance.
• Modified the tox configuration to include checks using mypy and flake8. However, I have commented out flake8 due to some errors. The proposed solution does not meet my requirements
• Updated variable names to resolve pep8 warnings from the PyCharm linter.
• Upgraded to stable dependencies.

Traceback if I run flake8 in terminal

Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Scripts\flake8.exe\__main__.py", line 7, in <module>
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Lib\site-packages\flake8\main\cli.py", line 22, in main
    app.run(argv)
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Lib\site-packages\flake8\main\application.py", line 363, in run
    self._run(argv)
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Lib\site-packages\flake8\main\application.py", line 350, in _run
    self.initialize(argv)
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Lib\site-packages\flake8\main\application.py", line 330, in initialize
    self.find_plugins(config_finder)
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Lib\site-packages\flake8\main\application.py", line 153, in find_plugins
    self.check_plugins = plugin_manager.Checkers(local_plugins.extension)
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Lib\site-packages\flake8\plugins\manager.py", line 356, in __init__
    self.manager = PluginManager(
                   ^^^^^^^^^^^^^^
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Lib\site-packages\flake8\plugins\manager.py", line 238, in __init__
    self._load_entrypoint_plugins()
  File "D:\Progrramming\PycharmProjects\python-rsa\.venv\Lib\site-packages\flake8\plugins\manager.py", line 254, in _load_entrypoint_plugins
    eps = importlib_metadata.entry_points().get(self.namespace, ())
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'EntryPoints' object has no attribute 'get'