build(deps): bump k256 from 0.13.3 to 0.13.4

Bumps [k256](https://github.com/RustCrypto/elliptic-curves) from 0.13.3 to 0.13.4.
- [Commits](RustCrypto/elliptic-curves@k256/v0.13.3...k256/v0.13.4)

---
updated-dependencies:
- dependency-name: k256
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>