ruff

f8c20258 - [red-knot] Do not panic on f-string format spec expressions (#14436)

[red-knot] Do not panic on f-string format spec expressions (#14436) ## Summary Previously, we panicked on expressions like `f"{v:{f'0.2f'}}"` because we did not infer types for expressions nested inside format spec elements. ## Test Plan ``` cargo nextest run -p red_knot_workspace -- --ignored linter_af linter_gz ```