v1.4.0

What's Changed

• feat: remove get_bots() method, as requested by Veld
• refactor: the urlencoding dependency is now only installed when the webhook feature flag is enabled
• refactor: refactor the serenity_handler! macro by utilizing the paste dependency
• doc: README and docs.rs related documentation tweaks

Full Changelog: v1.3.1...v1.4.0