chore(deps): bump ethers from 5.6.7 to 5.6.8 (argentlabs#685)

Bumps [ethers](https://github.com/ethers-io/ethers.js/tree/HEAD/packages/ethers) from 5.6.7 to 5.6.8.
- [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/v5.6.8/packages/ethers)

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

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