build(deps): bump third_party/flash_proxies from 01d8f81 to 3a06aa8

Bumps [third_party/flash_proxies](https://github.com/jordens/bscan_spi_bitstreams) from `01d8f81` to `3a06aa8`.
- [Release notes](https://github.com/jordens/bscan_spi_bitstreams/releases)
- [Commits](quartiq/bscan_spi_bitstreams@01d8f81...3a06aa8)

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