Pydicom v2.4 Release

[darcymason]

I'm thinking of a pydicom v2.4 release as the last one before we put together the Roadmap (see #1759) and start preparations towards Pydicom 3.0 (#1232). I believe this matches with previous discussions we have had.

In addition to the usual checklist below, I think it is time to make the jump to the pyproject.toml based packaging. This was discussed somewhat in #1593, perhaps elsewhere. I've made a start on it, and can do a PR for that. It could be delayed until v3.0, but that might take a while, and it would be nice to handle any packaging issues before the major release.

Release check list (more information)

• update packaging to modern recommendations - started, will finish for v3.0dev
• go through issues and close, assign to this version, or assign to future versions
• ensure deprecated classes, functions, etc. scheduled for removal have been removed - checked, don't seem to be any
• update to newest DICOM standard, and update __dicom_version__ in pydicom/_version.py - Dicom2023b #1803
• go through PRs to see which can be pulled in before release
• update the version in pydicom/_version.py to release
• check in the changes and create a branch and a GitHub release
• Check in Github Actions that the release workflow has completed
• get the new DOI at https://zenodo.org/account/settings/github/repository/pydicom/pydicom),
  and update the README.md in the release branch
• update documentation version on GitHub Pages
• update the version in pydicom/_version.py in master to next development version (major.minor.0.dev0),
  and update the DOI in the README.md
• merge auto-generated PR in conda-forge pydicom-feedstock
• announce on pydicom google group