Release version 0.9.0

Implement `fn remove_all`; update RELEASES.md

Implement `fn remove`

Allow making instances of `BitVec` with `B≠u32`

Previously it was not possible to construct such instances of `BitVec`
other than using the `Default` trait.

Maintenance

Fereidani's first contribution

chore(ci): upgrade checkout to v5

Enable some clippy lints

Maintain README, github workflow, MSRV

fix arg name in `with_capacity` and `from_elem`

Added `nth` to `BitVec::Iter` so that `.skip(n)` gets optimized

fix the `insert` panic message

Initial impl of `push_within_capacity`