DOC: Use pyproj to generate 2D latlon & fix cartopy UTM CRS

[snowman2]

• Passes pre-commit run --all-files

Using pyproj should be more efficient & simpler to use.

With latest cartopy, I get this error with 18N:

CRSError: Invalid projection: +proj=utm +ellps=WGS84 +units=m +zone=18N +no_defs +type=crs: (Internal Proj Error: proj_create: Error 1027 (Invalid value for an argument): utm: Invalid value for zone)

Removing N fixes the issue.

[github-actions]

Unit Test Results

         6 files  ±0           6 suites  ±0   57m 28s ⏱️ ±0s
16 227 tests ±0  14 492 ✔️ ±0  1 735 💤 ±0  0 ❌ ±0 
90 558 runs  ±0  82 384 ✔️ ±0  8 174 💤 ±0  0 ❌ ±0 

Results for commit bfff7f1. ± Comparison against base commit bfff7f1.

♻️ This comment has been updated with latest results.

[dcherian]

Thanks @snowman2