Update cartopy link

Author: dstansby

cheatsheets.tex

@@ -522,7 +522,7 @@
   \scale{projection-3d.pdf}
       {p='3d'\hfill\api{https://matplotlib.org/stable/api/toolkits/mplot3d.html}}{}
   \plot{projection-cartopy.pdf}{p=ccrs.Orthographic()}
-       {https://scitools.org.uk/cartopy/docs/latest/reference/projections.html}
+       {https://cartopy.readthedocs.io/stable/reference/projections.html}
        {import cartopy.crs as ccrs}
        {}
   \end{myboxed}