Rust edition 2024 / 1.85 and bump gloo to 0.12 (#16)

* Migrate to Rust edition 2024 and require Rust 1.85

- Set edition to 2024 and rust-version to 1.85
- Replace once_cell::sync::Lazy with std::sync::LazyLock
- Remove redundant std::future::Future imports (now in prelude)
- Remove bare_trait_objects and anonymous_parameters from deny list (hard errors in edition 2024)
- Switch cfg(documenting) to cfg(docsrs) for check-cfg compatibility
- Apply edition 2024 rustfmt formatting

* chore: gloo from 0.11 to 0.12

* v0.3.0

* Remove unused --cfg releasing from CI

v0.2.1

Remove the removed `doc_auto_cfg` feature flag that prevented docs
from building on nightly.

Closes #15

Remove prokio text from docs.