build(deps): bump litex/deps/litex from cdaf8af to e257ff9

Bumps [litex/deps/litex](https://github.com/enjoy-digital/litex) from `cdaf8af` to `e257ff9`.
- [Commits](enjoy-digital/litex@cdaf8af...e257ff9)

---
updated-dependencies:
- dependency-name: litex/deps/litex
  dependency-type: direct:production
...

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