feat: add listing logger channels in a guild

This commit also allows in the database to hold more than one channel
per guild and introduces clippy linting.

Closes #2

BREAKING CHANGES: The database schema changed from its root. All
databases should be dropped and recreated before running this new
version.

src/main.rs

@@ -1,3 +1,5 @@
+#![warn(clippy::style, clippy::pedantic)]
+
 mod utils;
 mod db;
 mod discord;
@@ -10,7 +12,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
     color_eyre::install()?;
     utils::setup_logging();
 
-    let bot = discord::make_bot().await?;
+    let bot = discord::make_bot();
     bot.run().await?;
 
     Ok(())