add netcdf4 dependency

Author: mmyrte

requirements/env_climada.yml

@@ -8,6 +8,7 @@ dependencies:
   - h5py=2.7.1
   - jsonschema=2.6.0
   - matplotlib=2.2.2
+  - netcdf4=1.4.0
   - numba=0.37.0
   - numpy=1.14.2
   - pandas=0.23.0