Update to 5.6.1

[Anthchirp]

Checklist

• [x] Used a fork of the feedstock to propose changes
• [ ] Bumped the build number (if the version is unchanged)
• [x] Reset the build number to 0 (if the version changed)
• [x] Re-rendered with the latest conda-smithy (Use the phrase code>@<space/conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• [x] Ensured the license file is being packaged.

Following the rerender this will drop Python 2.7 builds, so remove 2.7-specific instructions from the recipe. As a result the recipe becomes platform-independent.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[Anthchirp]

@conda-forge-admin, please rerender

[Anthchirp]

Wondering whether the download should be from pypi rather than github :thinking: