v3.0.0 - Select V2

• BREAKING: miru.Select has been renamed to miru.TextSelect along with the decorator miru.select to miru.text_select.
• BREAKING: miru.ext.nav.NavSelect has been renamed to miru.NavTextSelect.
• Added miru.UserSelect, miru.RoleSelect, miru.ChannelSelect, miru.MentionableSelect along with their respective decorators.
• Added Nav variants of all new selects to miru.ext.nav.
• Added miru.ext.nav.NavigatorView.swap_pages() to allow mutating the pages of a navigator after instantiation.
• Added initial framework and CI for unit testing in the library.
• Improved the validation of item properties.
• Added note about miru.load and miru.unload being removed in 3.1.0 to deprecation warning.
• Fixed TextInput.min_length and TextInput.max_length not being able to be set to None.
• Minor documentation and other fixes.