avoid std::prelude imports #3027

Job	Run time
Clippy	41s
Cargo Deny	23s
Build+test (--features alloc, ubuntu-latest, stable)	1m 5s
Build+test (--no-default-features --features alloc, ubuntu-latest, stable)	1m 8s
Check semver compatibility	19s
Build+test (--all-features, ubuntu-latest, stable)	1m 6s
Check cross compilation targets	38s
Check for documentation errors (beta)	19s
Verify that no-std modes do not rely on libstd (--no-default-features --features alloc)	15s
Build+test (ubuntu-latest, stable)	1m 5s
Measure coverage	1m 11s
Validate external types appearing in public API	17s
Build+test (--no-default-features, ubuntu-latest, stable)	55s
Feature Powerset	18s
MSRV	13s
Format	16s
Check for documentation errors (nightly)	16s
Check for documentation errors (stable)	17s
Verify that no-std modes do not rely on libstd (--no-default-features)	15s
Cargo Package	20s
	11m 17s

Provide feedback