Update to serenity 0.12.4 #1206

Job	Run time
Clippy	56s
Clippy	56s
Test (MSRV)	1m 25s
Test (MSRV)	1m 25s
Rustfmt	9s
Rustfmt	9s
Test (stable)	1m 57s
Test (stable)	1m 57s
Build docs	2m 20s
Build docs	2m 5s
Test (beta)	2m 11s
Test (beta)	2m 11s
Test (nightly)	1m 52s
Test (nightly)	1m 52s
Test (macOS)	1m 58s
Test (macOS)	1m 58s
Test (Windows)	5m 7s
Test (Windows)	5m 7s
Test (no features)	1m 9s
Test (no features)	1m 9s
Test (all features - simdjson, cargo test --all-features --lib --tests --examples)	1m 14s
Test (all features - simdjson, cargo test --all-features --lib --tests --examples)	1m 14s
Test (native TLS, cargo test --all-features --features serenity/native_tls_backend --lib --tests ...	1m 15s
Test (native TLS, cargo test --all-features --features serenity/native_tls_backend --lib --tests ...	1m 15s
	42m 51s

Provide feedback