0653/merge plot polar contour

[b-barton]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• [x ] Docs have been reviewed and added / updated if needed (for bug fixes / features)
  • Some docs updates need to be made in the COAsT-site repo, in a separate PR. See contributing to documentation for details.
• [x ] Build (./build.sh) was run locally and no errors reported. NB not sure about this requirement: GitActions test this
• [x ] Lint (pylint .) has passed locally and any fixes were made for failures. NB not sure about this requirement: GitActions test this with black

Pull request type

Please check the type of change your PR introduces:

• [x ] Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

The plot_util.plot_polar_contour() function wasn't working as expected. This could be tested using example_scripts\configuration_gallery\gc31_arctic_example_plot.py and looking at the output figure. The contours do not wrap correctly.

Issue URL: #653

What is the new behavior?

The cartopy solution has been put in. A transform=ccrs.epsg(3413) is needed in the .contour() so I've taken out the use of pyproj. This now plots contours correctly with example_scripts\configuration_gallery\gc31_arctic_example_plot.py

Checklist

• [x ] Code compiles correctly
• Created tests which fail without the change (if possible)
• [x ] All tests passing (pip install . && pytest unit_testing/unit_test.py -s)
• Extended the README / documentation, if necessary
• [x ] Added myself / the copyright holder to the AUTHORS file

Does this introduce a breaking change?

• Yes
• [x ] No

Other information

[b-barton]

I've no idea how these black formatting things work. It failed. Then I changed stuff, it still failed. I changed stuff back and it works?????