Update pre-commit hooks + mypy fixes

[dstansby]

Replaces #3109.

[dstansby]

@d-v-b any ideas what's going on with the typing error here? I can't wrap my head around why it's erroring. Perhaps we should just stick an # type: ignore comment on the failing line?

[DimitriPapadopoulos]

I wonder whether this would fix the mypy error:

-    if dtype_category == "variable-length-string":
-        zdtype = VariableLengthUTF8()
-    else:
-        zdtype = Int8()
+    if dtype_category == "variable-length-string":
+        zdtype = VariableLengthUTF8
+    else:
+        zdtype = Int8

[dstansby]

The issue with the dtype mypy error was the variable length string type is not actually a valid ZarrDtype. Since there are existing #type: ignore comments to acocunt for this, I added another one here.

[d-v-b]

@d-v-b any ideas what's going on with the typing error here? I can't wrap my head around why it's erroring. Perhaps we should just stick an # type: ignore comment on the failing line?

which specific typing error? a basic challenge with VariableLengthUTF8 is that it's conditionally defined: if numpy < 2 is installed, we define 1 version of the class (using the numpy object dtype) and if numpy > 2 is installed, we define a different version of the class (using np.dtypes.StringDType). That can be why mypy singles this type out as unknown

[dstansby]

This line here: https://github.com/zarr-developers/zarr-python/pull/3133/files#diff-da24b355349b53e4c8047034767d008e4c2ce9ea6c8933a3acd50d0828f00528R334 - if you remove the typing ignores, it gives an error.

[d-v-b]

This line here: https://github.com/zarr-developers/zarr-python/pull/3133/files#diff-da24b355349b53e4c8047034767d008e4c2ce9ea6c8933a3acd50d0828f00528R334 - if you remove the typing ignores, it gives an error.

yeah, mypy is confused there, so the type ignore is correct. This will get simpler in a few months when we drop numpy < 2.