Automating release

To simplify the release process, wonder if it would be worthwhile to bake most of [the release steps]( https://github.com/dask/dask-image/blob/264bd1d842cb6e4c8df24492ed303c32ab7222e1/docs/release/release_guide.rst ) into a GHA workflow that responds to a `git tag`

It could for example [generate release notes that are included in a GitHub release]( https://github.com/marketplace/actions/github-create-tag-release ). Also it could [create the `whl` & `sdist` artifacts and upload them to PyPI]( https://github.com/zarr-developers/zarr-python/blob/6ed4d785db71d7087b276f0f6dc5b3f7cfedd7f1/.github/workflows/releases.yml )

The conda-forge bot already submits new releases. Though we could start them more quickly using the [`@conda-forge-admin, please update version` bot request]( https://conda-forge.org/docs/maintainer/infrastructure.html#conda-forge-admin-please-update-version ) in [a `dask-image` feedstock issue]( https://github.com/conda-forge/dask-image-feedstock/issues/new?assignees=&labels=&projects=&template=2-bot-commands.yml )