update to conda-build-3

[looooo]

testing conda-build3

Thank you for pull request.

Below are a few things we ask you kindly to self-check before getting a review.

• [ ] Used a fork of the feedstock to propose changes
• [ ] Bump the build number (if the version is unchanged)
• [ ] Reset the build number to 0 (if the version changed)
• [ ] Re-render with the latest conda-smithy
• [ ] Ensure the license file is being packaged.

Please note any issues this fixes using closing keywords:

Please add any other relevant info below:

[conda-forge-linter]

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

I wanted to let you know that I linted all conda-recipes in your PR (recipe) and found some lint.

Here's what I've got...

For recipe:

• Failed to even lint the recipe (might be a conda-smithy bug) :cry: