Update cartopy requirement from ~=0.22 to ~=0.23 (#56)

Updates the requirements on [cartopy](https://github.com/SciTools/cartopy) to permit the latest version.
- [Release notes](https://github.com/SciTools/cartopy/releases)
- [Commits](SciTools/cartopy@v0.22.0...v0.23.0)

---
updated-dependencies:
- dependency-name: cartopy
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -1,4 +1,4 @@
 numpy~=1.26
 matplotlib~=3.8
-cartopy~=0.22
+cartopy~=0.23
 pygame~=2.5