build(deps): update boring requirement from 4.3 to 5.1

Updates the requirements on [boring](https://github.com/cloudflare/boring) to permit the latest version.
- [Release notes](https://github.com/cloudflare/boring/releases)
- [Changelog](https://github.com/cloudflare/boring/blob/master/RELEASE_NOTES)
- [Commits](cloudflare/boring@v4.3.0...v5.1.0)

---
updated-dependencies:
- dependency-name: boring
  dependency-version: 5.1.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Cargo.toml

@@ -34,7 +34,7 @@ publish = false
 [workspace.dependencies]
 anyhow = { version = "1" }
 assert_matches = { version = "1" }
-boring = { version = "4.3" }
+boring = { version = "5.1" }
 buffer-pool = { version = "0.2.1", path = "./buffer-pool" }
 bytes = { version = "1.11.1" }
 crossbeam = { version = "0.8.1", default-features = false }