`fix` can't handle source files encoded as UTF-8

[bkeryan]

We are adding a nidaqmx-python test containing localized strings:

@pytest.mark.parametrize(
    "device_name, supported_encodings",
    [
        ("Gerät", ["1252", "iso-8859-1", "utf-8"]),
        ("l' appareil", ["1252", "iso-8859-1", "utf-8"]),
        ("デバイス", ["932", "shift-jis", "utf-8"]),
        ("장치", ["utf-8", "euc-kr"]),
        ("设备", ["utf-8", "gbk"]),
    ],
)
...

Reformatting this test with ni-python-styleguide fix fails with this error:

PS D:\dev\nidaqmx-python> poetry run ni-python-styleguide fix
All done! ✨ 🍰 ✨
1 file left unchanged.
Traceback (most recent call last):
  File "C:\Users\Administrator\.pyenv\pyenv-win\versions\3.9.13\lib\runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\Administrator\.pyenv\pyenv-win\versions\3.9.13\lib\runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "D:\dev\nidaqmx-python\.venv\Scripts\ni-python-styleguide.exe\__main__.py", line 7, in <module>
  File "D:\dev\nidaqmx-python\.venv\lib\site-packages\click\core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
  File "D:\dev\nidaqmx-python\.venv\lib\site-packages\click\core.py", line 1078, in main
    rv = self.invoke(ctx)
  File "D:\dev\nidaqmx-python\.venv\lib\site-packages\click\core.py", line 1688, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "D:\dev\nidaqmx-python\.venv\lib\site-packages\click\core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "D:\dev\nidaqmx-python\.venv\lib\site-packages\click\core.py", line 783, in invoke
    return __callback(*args, **kwargs)
  File "D:\dev\nidaqmx-python\.venv\lib\site-packages\click\decorators.py", line 45, in new_func
    return f(get_current_context().obj, *args, **kwargs)
  File "D:\dev\nidaqmx-python\.venv\lib\site-packages\ni_python_styleguide\_cli.py", line 186, in fix
    _fix.fix(
  File "D:\dev\nidaqmx-python\.venv\lib\site-packages\ni_python_styleguide\_fix.py", line 146, in fix
    raise Exception(
Exception: Failed to format files:
D:\dev\nidaqmx-python\tests\acceptance\test_internationalization.py: 'charmap' codec can't decode byte 0x90 in position 996: character maps to <undefined>

Workarounds:

• Fix errors manually. ni-python-styleguide lint doesn't seem to have this problem.
• Avoid UTF-8 in source files. Use "\uXXXX" escapes instead.