v0.4.0

What's Changed

• refactor: serenity and idle handlers in their modules & commands struct by @joao-conde in #73
• fix: bot activity using configured prefix by @joao-conde in #74
• test: util module tests by @joao-conde in #75
• refactor: transfer main binary to lib code by @joao-conde in #77
• Update Cargo.toml by @joao-conde in #78
• Deployment by @afonsojramos in #79
• Update cargo.toml by @afonsojramos in #80

Full Changelog: v0.3.0...v0.4.0