Fix broken links

[dshean]

Compiled by @egagli:

Module 3: https://pandas.pydata.org/pandas-docs/stable/getting_started/10min.html matplotlib links still work but updated version available need to be logged in for NSIDC link to work Module 4: Last geopandas link is intermediate, consider linking to actual examples gallery Module 5: https://landsat.usgs.gov/how-does-landsat-8s-12-bit-data-improve-data-products broken https://github.com/OSGeo/gdal/tree/master/gdal/swig/python/samples broken ex2: https://gsp.humboldt.edu/OLM/Courses/GSP_216_Online/lesson3-1/composites.html broken Module 6: https://trac.osgeo.org/geos/ moved Module 7: https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter13_FINAL.pdf consider using new IPCC report chapter Module 8: https://www.wcc.nrcs.usda.gov/about/mon_automate.html https://www.wcc.nrcs.usda.gov/snotel/snotel_sensors.html Module 9: ex1: https://confluence.ecmwf.int/display/CKB/What+is+ERA5 http://datastore.copernicus-climate.eu/c3s/published-forms/c3sprod/ecv-for-climate-change/PUG-ecv-for-climate-change.pdf

[scottyhq]

Added a link checking github action that can be run manually

Log here: https://github.com/UW-GDA/jupyterbook/runs/4681792550?check_suite_focus=true

[scottyhq]

Just re-ran the linkcheck workflow: https://github.com/UW-GDA/jupyterbook/actions/runs/3832299782/jobs/6522446977