Bump firrtl from `22eb7bb` to `a4aef0f` (#275)

Bumps [firrtl](https://github.com/freechipsproject/firrtl) from `22eb7bb` to `a4aef0f`.
- [Release notes](https://github.com/freechipsproject/firrtl/releases)
- [Commits](https://github.com/freechipsproject/firrtl/compare/22eb7bb8c758ce93018062b62c67f687e66c274b...a4aef0f6219d45cafa13d97cd3a977d5761de21e

)

---
updated-dependencies:
- dependency-name: firrtl
  dependency-type: direct:production
...

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