Drop support for Python3.6

[cacharle]

3.6 has reached end of life so it should be dropped.

Also would be nice to add Python3.11 in the CI.

[cacharle]

Is becoming more necessary for https://github.com/cacharle/c_formatter_42/pull/17

[keyhr]

Are the tasks listed below enough for this issue?

• Remove Python3.6 and Add Python3.11 from these lines
  • https://github.com/dawnbeen/c_formatter_42/blob/bbcf19a995740db64dce8c07aa23b41ee90f0098/tox.ini#L2
  • https://github.com/dawnbeen/c_formatter_42/blob/bbcf19a995740db64dce8c07aa23b41ee90f0098/README.md?plain=1#L22
  • https://github.com/dawnbeen/c_formatter_42/blob/bbcf19a995740db64dce8c07aa23b41ee90f0098/setup.cfg#L11-L15
  • https://github.com/dawnbeen/c_formatter_42/blob/bbcf19a995740db64dce8c07aa23b41ee90f0098/setup.cfg#L25
• Rerun the CI

[cacharle]

Need to remove it from CI aswell

https://github.com/dawnbeen/c_formatter_42/blob/bbcf19a995740db64dce8c07aa23b41ee90f0098/.github/workflows/python-package-develop.yml#L26