ruff

ae9d450b - [ty] Fallback to Unknown if no type is stored for an expression (#19517)

[ty] Fallback to Unknown if no type is stored for an expression (#19517) ## Summary See discussion at https://github.com/astral-sh/ruff/pull/19478/files#r2223870292 Fixes https://github.com/astral-sh/ty/issues/865 ## Test Plan Added one mdtest for invalid Callable annotation; removed `pull-types: skip` from that test file. Co-authored-by: lipefree <willy.ngo.2000@gmail.com>