Bump third_party/prjxray from `5715970` to `3b3b347`
Bump third_party/prjxray from `5715970` to `3b3b347`

Bumps [third_party/prjxray](https://github.com/SymbiFlow/prjxray) from `5715970` to `3b3b347`.
- [Release notes](https://github.com/SymbiFlow/prjxray/releases)
- [Commits](https://github.com/SymbiFlow/prjxray/compare/5715970e7d55b33d9d963e99cb29276df72b31cd...3b3b347af581639506d388e3fce8fd9fe4a876c3)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
SymbiFlow/symbiflow-xc-fasm2bels