Bump formidable and smee-client

Removes [formidable](https://github.com/node-formidable/formidable). It's no longer used after updating ancestor dependency [smee-client](https://github.com/probot/smee-client). These dependencies need to be updated together.


Removes `formidable`

Updates `smee-client` from 1.2.3 to 2.0.1
- [Release notes](https://github.com/probot/smee-client/releases)
- [Commits](probot/smee-client@v1.2.3...v2.0.1)

---
updated-dependencies:
- dependency-name: formidable
  dependency-type: indirect
- dependency-name: smee-client
  dependency-type: direct:development
...

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Author: dependabot[bot]