build(deps-dev): bump ethers from 5.1.0 to 5.6.9

Bumps [ethers](https://github.com/ethers-io/ethers.js/tree/HEAD/packages/ethers) from 5.1.0 to 5.6.9.
- [Release notes](https://github.com/ethers-io/ethers.js/releases)
- [Changelog](https://github.com/ethers-io/ethers.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/ethers-io/ethers.js/commits/v5.6.9/packages/ethers)

---
updated-dependencies:
- dependency-name: ethers
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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