Bump async, web-ext and web-ext-submit

Bumps [async](https://github.com/caolan/async) to 3.2.5 and updates ancestor dependencies [async](https://github.com/caolan/async), [web-ext](https://github.com/mozilla/web-ext) and [web-ext-submit](https://github.com/fregante/web-ext-submit). These dependencies need to be updated together.


Updates `async` from 2.6.3 to 3.2.5
- [Release notes](https://github.com/caolan/async/releases)
- [Changelog](https://github.com/caolan/async/blob/master/CHANGELOG.md)
- [Commits](caolan/async@v2.6.3...v3.2.5)

Updates `web-ext` from 4.3.0 to 8.2.0
- [Release notes](https://github.com/mozilla/web-ext/releases)
- [Commits](mozilla/web-ext@4.3.0...8.2.0)

Updates `web-ext-submit` from 4.1.0 to 7.8.0
- [Commits](fregante/web-ext-submit@v4.1.0...v7.8.0)

---
updated-dependencies:
- dependency-name: async
  dependency-type: indirect
- dependency-name: web-ext
  dependency-type: direct:development
- dependency-name: web-ext-submit
  dependency-type: direct:development
...

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