Remove somewhat useless setup function #990

Job	Run time
Rustfmt	8s
Test (MSRV)	1m 19s
Clippy	47s
Test (stable)	1m 57s
Build docs	1m 24s
Test (beta)	2m 4s
Test (nightly)	2m 0s
Test (macOS)	3m 32s
Test (Windows)	4m 52s
Test (no features)	1m 12s
Test (all features - simdjson, cargo test --all-features --lib --tests --examples)	1m 13s
Test (native TLS, cargo test --all-features --features serenity/native_tls_backend --lib --tests ...	1m 14s
	21m 42s

Provide feedback