Prepare conda release.

Following work elsewhere, this package can be modernised with current packaging/release techniques such as pyproject.toml, versioneer etc.

Adding this issue for when I or someone else has time to do the refactoring.

Start by inspecting the repository's current packaging and release configuration, then compare it with the proposed pyproject.toml and versioneer approaches. Define the required conda release workflow and agree on the refactoring scope before making changes; done means the package can be released through the intended modernized process.

Written by the indexing model from the issue text.