v0.7.4

Thank you for all the contributions!

Fixes

• Fix verification of requests from Slack in example code #863 by @kanata2
• Fix test for conversations.mark #866 by @kanata2
• Remove the unnecessary parameter from SetUserRealName and update optional param handling in profile setting #868 by @sryoya

Features

• [Feat] conversations.mark #761 by @ramikalai

Improvement

• Implement an error-comparing method to errorsx String #841 by @sryoya
• Avoid returning correct signature #862 by @tyrannosaurus-becks

Misc

• Add issue templates #864 by @kanata2