Remove deprecated RawConfigParser (deprecated in python 3.12)

[Thanhphan1147]

Hi,

I believe python 3.12 has removed SafeConfigParser.

This issue has been raised across multiple projects: here are a few examples:

• Config Parser deprecated issue lra/mackup#1948
• AttributeError: module 'configparser' has no attribute 'SafeConfigParser' pydata/pandas-datareader#969

I don't find any other references of SafeConfigParser in the repo, so I assume it'll be safe to remove it. Please let me know if that's not the case.

Here is the error when running pflake8 with python3.12

$ pflake8
Traceback (most recent call last):
  File "/home/ubuntu/flask-multipass-saml-groups/.tox/lint/bin/pflake8", line 5, in <module>
    from pflake8.__main__ import main
  File "/home/ubuntu/flask-multipass-saml-groups/.tox/lint/lib/python3.12/site-packages/pflake8/__init__.py", line 54, in <module>
    class DivertingSafeConfigParser(ConfigParserTomlMixin, configparser.SafeConfigParser):
                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'configparser' has no attribute 'SafeConfigParser'. Did you mean: 'RawConfigParser'?

[Thanhphan1147]

oops, just realized that there's already a PR for this.

[csachs]

Thanks for the PR, fixed with #28 now.