Bump elliptic-curve from 0.13.6 to 0.13.8

Bumps [elliptic-curve](https://github.com/RustCrypto/traits) from 0.13.6 to 0.13.8.
- [Commits](RustCrypto/traits@elliptic-curve-v0.13.6...elliptic-curve-v0.13.8)

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

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