build(deps): update hashbrown requirement from 0.14 to 0.15 (#2341)

Updates the requirements on [hashbrown](https://github.com/rust-lang/hashbrown) to permit the latest version.
- [Changelog](https://github.com/rust-lang/hashbrown/blob/master/CHANGELOG.md)
- [Commits](rust-lang/hashbrown@v0.14.0...v0.15.0)

---
updated-dependencies:
- dependency-name: hashbrown
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

quic/s2n-quic-transport/Cargo.toml

@@ -20,7 +20,7 @@ unstable-provider-dc = []
 bytes = { version = "1", default-features = false }
 futures-channel = { version = "0.3", default-features = false, features = ["alloc"] }
 futures-core = { version = "0.3", default-features = false, features = ["alloc"] }
-hashbrown = "0.14"
+hashbrown = "0.15"
 intrusive-collections = "0.9"
 once_cell = "1"
 s2n-codec = { version = "=0.47.0", path = "../../common/s2n-codec", features = ["bytes"], default-features = false }