Allow docutils 0.18

[chohner]

Upstream now supports docutils 0.18, released as part of the 5.0.0 release

Checklist

• Used a personal 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)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-webservice.

It appears you are making a pull request from a branch in your feedstock and not a fork. This procedure will generate a separate build for each push to the branch and is thus not allowed. See our documentation for more details.

Please close this pull request and remake it from a fork of this feedstock.

Have a great day!

[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.

[chohner]

This isn't major breakage but stopping auto-merge might make sense here, as suggested in #117

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-webservice.

It appears you are making a pull request from a branch in your feedstock and not a fork. This procedure will generate a separate build for each push to the branch and is thus not allowed. See our documentation for more details.

Please close this pull request and remake it from a fork of this feedstock.

Have a great day!