build: upgrade packages to make this sphinx work

Author: hgrecco

.github/workflows/docs.yml

@@ -40,11 +40,11 @@ jobs:
           sudo apt install -y pandoc
           pip install --upgrade pip setuptools wheel
           pip install -r "requirements_docs.txt"
-          pip install docutils==0.14 commonmark==0.8.1 recommonmark==0.5.0 babel==2.8
+          pip install docutils commonmark==0.8.1 recommonmark==0.5.0 babel
           pip install .
 
       - name: Build documentation
-        run: sphinx-build -n -b html -d build/doctrees docs build/html
+        run: sphinx-build -n -j auto -b html -d build/doctrees docs build/html
 
       - name: Doc Tests
-        run: sphinx-build -a -b doctest -d build/doctrees docs build/doctest
+        run: sphinx-build -a -j auto -b doctest -d build/doctrees docs build/doctest

requirements_docs.txt

@@ -7,7 +7,6 @@ numpy
 pytest
 jupyter_client
 ipykernel
-ipython
 graphviz
 xarray
 pooch