MNT: Re-rendered with conda-smithy 3.1.12 and pinning 2018.08.21

[damianavila]

Checklist

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

@ocefpaf, I rerender the feedstock but I do not see python=3.7 reference to build py37 packages. What should I do to make it happen? Thanks.

[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.

[ocefpaf]

Done in #18