Bump fixed-hash from 0.7.0 to 0.8.0

Bumps [fixed-hash](https://github.com/paritytech/parity-common) from 0.7.0 to 0.8.0.
- [Release notes](https://github.com/paritytech/parity-common/releases)
- [Commits](https://github.com/paritytech/parity-common/compare/fixed-hash-v0.7.0...fixed-hash-v0.8.0)

---
updated-dependencies:
- dependency-name: fixed-hash
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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