Bump chisel3 from `7fc023cd` to `a931c5e2` (#310)

Bumps [chisel3](https://github.com/freechipsproject/chisel3) from `7fc023cd` to `a931c5e2`.
- [Release notes](https://github.com/freechipsproject/chisel3/releases)
- [Commits](https://github.com/freechipsproject/chisel3/compare/7fc023cd2983cc22a309636d3cd7e0d9066cd805...a931c5e218014c659bbff7d0dec74c882281d9a0

)

---
updated-dependencies:
- dependency-name: chisel3
  dependency-type: direct:production
...

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