attempt to fix documentation build problems

.gitlab-ci.yml

@@ -4,6 +4,7 @@ pages:
   - pip install -r requirements.txt
   - pip install cartopy
   - pip install nbsphinx nbsphinx_link pydata_sphinx_theme sphinx_copybutton
+  - pip install -e .
   - cd doc
   - make html
   - mv _build/html/* ../public/