Fix docs build - remove duplicate intersphinx entries

The prefix identifier (the duplicate of which was causing the docs
build to fail with recent sphinx versions), is only useful when linking
to pages. It's not used when resolving packages/modules/classes, so we
don't need the double ups for xr/xarray and np/numpy.

docs/conf.py

@@ -84,9 +84,7 @@
     "python": ("https://docs.python.org/3", None),
     "pyproj": ("https://pyproj4.github.io/pyproj/stable/", None),
     "numpy": ("https://numpy.org/doc/stable/", None),
-    "np": ("https://numpy.org/doc/stable/", None),
     "xarray": ("https://xarray.pydata.org/en/stable/", None),
-    "xr": ("https://xarray.pydata.org/en/stable/", None),
     "rasterio": ("https://rasterio.readthedocs.io/en/latest/", None),
     "shapely": ("https://shapely.readthedocs.io/en/latest/", None),
     "folium": ("https://python-visualization.github.io/folium/latest/", None),