Option to disable converting Jira issue prefix to uppercase

[KnifeFed]

I'm using commitlint with @commitlint/config-conventional which only allows lowercase subjects. Since this adapter converts the Jira prefix to uppercase, it fails linting when using the default jiraLocation: 'pre-description'. I've solved this for now by disabling the subject-case rule, but I would prefer to leave it intact, so I would really appreciate an option to not convert anything to uppercase. Even better would be an option to convert it to lowercase if it's typed in uppercase 🙂