Fix clippy warnings on current #6371

Job	Run time
Examples	4m 16s
Test (macOS)	1m 56s
Test (nightly)	2m 17s
MSRV	1m 17s
Check minimal versions	52s
Build docs	55s
Test (beta)	2m 3s
Test (native-tls)	1m 42s
Test (stable)	2m 2s
Test (Windows)	6m 6s
Test (no default features)	1m 0s
Test (unstable Discord API (no default features), unstable_discord_api, true)	44s
Test (no gateway)	1m 29s
Test (no cache)	2m 3s
Test (builder without model, builder, true)	35s
Test (unstable Discord API features)	2m 2s
Test (chrono, chrono)	54s
Test (simd-json)	2m 2s
Test (unstable API + typesize, default unstable_discord_api typesize, true)	1m 18s
	35m 33s

Provide feedback