ci(sdk-python): pin ruff to 0.15.22

ruff 0.16.0 released and the workflow installs unpinned ruff, so the Lint
step now fails with ~2700 pre-existing violations (I001, BLE001, C408, ...)
on every sdk-python PR — current main itself is red under 0.16.0 and clean
under 0.15.22. Pin the version CI actually validated against; bump
deliberately alongside the rule fixes.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: AbirAbbas