Bump mocha from 7.2.0 to 8.3.2 in /packages/arb-provider-ethers

Bumps [mocha](https://github.com/mochajs/mocha) from 7.2.0 to 8.3.2.
- [Release notes](https://github.com/mochajs/mocha/releases)
- [Changelog](https://github.com/mochajs/mocha/blob/master/CHANGELOG.md)
- [Commits](mochajs/mocha@v7.2.0...v8.3.2)

Signed-off-by: dependabot[bot] <support@github.com>

packages/arb-provider-ethers/package.json

@@ -49,7 +49,7 @@
     "chai-bignumber": "^3.0.0",
     "ethereum-waffle": "^2.3.0",
     "install-peers-cli": "^2.2.0",
-    "mocha": "^7.2.0",
+    "mocha": "^8.3.2",
     "nyc": "^15.1.0",
     "typescript": "^4.0.2"
   },