Add commit title message `max_length` option

[ryo246912]

Is your feature request related to a problem? Please describe.

Is there an option to set a character limit for the commit title message?

Describe the solution you'd like

I would like koji to have an option in config.toml to set a character limit for the title message.
On GitHub, if the title message exceeds 72 characters (I'm not certain of the exact number), it automatically gets truncated, affecting the appearance in the GitHub UI.
Additionally, I believe commit title messages should be concise and to the point, so having this setting would be valuable.
cf. https://robertcooper.me/post/git-commit-messages

Describe alternatives you've considered

None.

Additional context

I think this is a fantastic tool! I would love to use it actively and have a few requests.
I usually use czg, and I think koji could become an even more attractive tool by referencing some of its features.
czg has a setting maxSubjectLength, and I typically set it to 72 characters.
Although I occasionally use titles longer than 72 characters, this is generally an effective setting.