build(deps): bump third_party/python-sdf-timing
build(deps): bump third_party/python-sdf-timing

Bumps [third_party/python-sdf-timing](https://github.com/SymbiFlow/python-sdf-timing) from `f6e72dd` to `d557a5d`.
- [Release notes](https://github.com/SymbiFlow/python-sdf-timing/releases)
- [Commits](https://github.com/SymbiFlow/python-sdf-timing/compare/f6e72dd645010f7c38c57176e635caac699f427b...d557a5d438a8f512ded6d26b500599a436979c47)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
SymbiFlow/symbiflow-arch-defs,SymbiFlow/symbiflow-arch-defs