Ignore these mypy errors

[MTCam]

These errors are coming with the imminent update to latest inducer@main upstream pkgs. Tried, but didn't figure out how to get around them instance-by-instance.

https://github.com/illinois-ceesd/mirgecom/actions/runs/12190311488/job/34010485460?pr=926

Questions for the review:

• Is the scope and purpose of the PR clear?
  • The PR should have a description.
  • The PR should have a guide if needed (e.g., an ordering).
• Is every top-level method and class documented? Are things that should be documented actually so?
• Is the interface understandable? (I.e. can someone figure out what stuff does?) Is it well-defined?
• Does the implementation do what the docstring claims?
• Is everything that is implemented covered by tests?
• Do you see any immediate risks or performance disadvantages with the design? Example: what do interface normals attach to?