build(deps): bump fast-json-patch and web-ext in /addon (#1763)

Bumps [fast-json-patch](https://github.com/Starcounter-Jack/JSON-Patch) to 3.1.1 and updates ancestor dependency [web-ext](https://github.com/mozilla/web-ext). These dependencies need to be updated together.


Updates `fast-json-patch` from 2.2.1 to 3.1.1
- [Release notes](https://github.com/Starcounter-Jack/JSON-Patch/releases)
- [Commits](Starcounter-Jack/JSON-Patch@v2.2.1...3.1.1)

Updates `web-ext` from 7.4.0 to 7.5.0
- [Release notes](https://github.com/mozilla/web-ext/releases)
- [Commits](mozilla/web-ext@7.4.0...7.5.0)

---
updated-dependencies:
- dependency-name: fast-json-patch
  dependency-type: indirect
- dependency-name: web-ext
  dependency-type: direct:development
...

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