Releasing the Polar2Grid Python Package

Update setup.py with the new version.
Create a git tag for the new version:
```
git tag -a vX.Y.Z -m "Version X.Y.Z"
```
Push the tag to github:
```
git push --follow-tags
```
Create a GitHub release for this tag with name "Version X.Y.Z" and add release notes to the description.
The GitHub release will trigger various GitHub jobs to run. Make sure they succeed.