build(deps): bump third_party/picorv32 from f9b1beb to f00a88c (#410)

Bumps [third_party/picorv32](https://github.com/cliffordwolf/picorv32) from `f9b1beb` to `f00a88c`.
- [Release notes](https://github.com/cliffordwolf/picorv32/releases)
- [Commits](YosysHQ/picorv32@f9b1beb...f00a88c)

---
updated-dependencies:
- dependency-name: third_party/picorv32
  dependency-type: direct:production
...

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