Bump chisel3 from `cea238bb` to `a7703f53` (#308)

Bumps [chisel3](https://github.com/freechipsproject/chisel3) from `cea238bb` to `a7703f53`.
- [Release notes](https://github.com/freechipsproject/chisel3/releases)
- [Commits](https://github.com/freechipsproject/chisel3/compare/cea238bb9f6cb364d0c6c6229ff316eebc8224ec...a7703f539d4e232cd182ce4e996a4f3d049dfe7a

)

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

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