Resolve "Plotting CMIP6 data on unstructured grids with psyplot"

Closes #15 (closed)

environment.yml

@@ -24,7 +24,7 @@ dependencies:
   # testing
   - pytest
   - nbval
-#  - nbsphinx
+  - nbsphinx
   - nbconvert=5.6.1 #from envkernel
   - sphinx
   - esmvalcore
@@ -33,6 +33,5 @@ dependencies:
   - psy-maps
   - psyplot
   - pip:
-    - myst-nb
     - envkernel
     - shapely