Relax bounds on HashMap to match hashbrown
Relax bounds on HashMap to match hashbrown

No functional changes are made, and all APIs are moved to strictly less
restrictive bounds.

These APIs changed from the old bound listed to no trait bounds:

K: Hash + Eq
* new
* with_capacity

K: Eq + Hash, S: BuildHasher
* with_hasher
* with_capacity_and_hasher
* hasher

K: Eq + Hash + Debug -> K: Debug
S: BuildHasher -> S
<HashMap as Debug>

K: Eq + Hash -> K
S: BuildHasher + Default -> S: Default
<HashMap as Default>

aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust