Bump sanic from 21.9.3 to 21.12.0

Bumps [sanic](https://github.com/sanic-org/sanic) from 21.9.3 to 21.12.0.
- [Release notes](https://github.com/sanic-org/sanic/releases)
- [Changelog](https://github.com/sanic-org/sanic/blob/main/CHANGELOG.rst)
- [Commits](sanic-org/sanic@v21.9.3...v21.12.0)

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

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