Don't install cupy-core 14.0.0 or 14.0.1 in readthedocs build

Avoid `TypeError: expected str, bytes or os.PathLike object, not NoneType`. Xref cupy/cupy#9777

Author: weiji14

ci/doc.yml

@@ -2,7 +2,7 @@ name: cupy-xarray-doc
 channels:
   - conda-forge
 dependencies:
-  - cupy-core
+  - cupy-core!=14.0.0,!=14.0.1 # https://github.com/cupy/cupy/issues/9777
   - pip
   - python=3.10
   - sphinx