Fix mypy errors

[vyasr]

There are a few issues that needed fixing:

• The current requirements file is no longer current enough to be solvable because the pinned polars-cloud release of 0.0.11 doesn't actually exist on PyPI. I had uv compile a new set of requirements to fix that, which led to the subsequent issues.
• The various new releases of polars-cloud since the last time this repository was updated have presumably led to some of the changes. I can't say for sure exactly what changed since I don't have access to polars cloud source code.
  • I could remove an attr-defined on the SchedulerClient. Not sure why, I didn't look at the old definition to find out.
  • I had to cast a query result. I'm guessing that this is because other result types didn't exist when this code was first added.
• There was in indentation where get_status was being created as a free function rather than as a method on the PatchedComputeContext class. That wasn't triggering any mypy issues, but it was a clear bug so I fixed it.
• DuckDB has temporarily lost typing due to the 1.4 release. We should be able to revert that change once they get it fixed, but in the meantime it would be good to get CI unblocked on this repo.

[ritchie46]

Thanks!