New release planned: v9.3.6

This is to inform the community that a new release is being prepared.

• Read steps in the how-to-contribute docs for making a release
• Merge request to update changelog and bump version
• Merge MR (this is the last MR for the release)
• Make sure CI is OK on develop branch
• Make sure the documentation is updated for develop (readthedocs)
• Merge develop into stable
• Make sure CI and Appveyor are OK on stable branch
• Make sure the documentation is updated for stable (readthedocs)
• Create an annotated tag from develop branch
• Make sure the documentation is updated for release (readthedocs)
• Upload the new version to PyPI
• Bump the version with “-dev” in the develop branch
• Create and fill in the release description on GitLab
• Build conda packages
• Advertise the release on the mailing list
• Close this issue