CI: pin numpydoc==1.8.0 to unblock docstring validation

Author: evgenii

environment.yml

@@ -84,7 +84,7 @@ dependencies:
   # documentation
   - gitpython  # obtain contributors from git for whatsnew
   - natsort  # DataFrame.sort_values doctest
-  - numpydoc
+  - numpydoc=1.8.0
   - pydata-sphinx-theme=0.16
   - pytest-cython  # doctest
   - sphinx

requirements-dev.txt

@@ -59,7 +59,7 @@ tokenize-rt
 pre-commit>=4.2.0
 gitpython
 natsort
-numpydoc
+numpydoc==1.8.0
 pydata-sphinx-theme==0.16
 pytest-cython
 sphinx