Bump ethers from 5.5.4 to 5.6.0 (#56)

Bumps [ethers](https://github.com/ethers-io/ethers.js/tree/HEAD/packages/ethers) from 5.5.4 to 5.6.0.
- [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/v5.6.0/packages/ethers)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -50,7 +50,7 @@
     "eslint-plugin-prettier": "^3.4.1",
     "eslint-plugin-promise": "^5.2.0",
     "ethereum-waffle": "^3.4.0",
-    "ethers": "^5.5.3",
+    "ethers": "^5.6.0",
     "hardhat": "^2.8.3",
     "hardhat-gas-reporter": "^1.0.7",
     "prettier": "^2.5.1",