Replace mime-types gem with mini_mime

[orien]

Description

mini_mime is a minimal mime type library that's more performant and uses less memory than the mime-types gem.

It has replaced mime-types in several projects:

• rails → actionmailer → mail gem: Switch to mini_mime for memory savings mikel/mail#1059
• capybara Switch to mini_mime gem from mime-types teamcapybara/capybara#1884
• httparty Suggestion: Replace mime-types with mini_mime for content type lookup jnunemaker/httparty#769

Using it as a dependency of cucumber, downstream projects would be able to reuse the same dependency that is already available in most Rails apps, instead of pulling in an extra mime-types dependency.

Type of change

• Refactoring (of dependencies) (improvements to code design or tooling that don't change behaviour)

Checklist

• Tests have been added for any changes to behaviour of the code
• New and existing tests are passing locally and on CI
• bundle exec rubocop reports no offenses
• RDoc comments have been updated
• CHANGELOG.md has been updated

[luke-hill]

I will get to this. Sorry for delays. Just starting a new job and still configuring all my emails / IDE's e.t.c.