feat: Add `conda` package

[ajschmidt8]

This PR adds a conda package for dfg.

It also updates the GHAs workflows to accommodate building the conda and wheel packages in separate jobs (to ensure clean environments).

Since semantic-release is intended to deploy release artifacts from a single machine, this required updating the release workflow to do the following:

• Run semantic-release with the --dry-run flag first. The --dry-run flag enables the workflow to determine whether the most recent changes warrant a release.
• If the most recent changes warrant a release, run the build/test workflow. This builds the conda and wheel packages on separate machines to ensure build isolation. The artifacts are then uploaded with actions/upload-artifact.
• Once the build/test workflow is complete, the final release job downloads the artifacts with actions/download-artifact and deploys them with semantic-release.

[ajschmidt8]

Things to do/check after this is merged:

• [x] Ensure packages are published to PyPI and Anaconda.org correctly
• [ ] Ensure links in PR release comments are correct (e.g. these)
• [x] Ensure automated commits work correctly after release (e.g. these)
• [x] Ensure CI images still get triggered correctly after successful release (e.g. this workflow)
• [x] Update required checks for this repository to reflect new job names

[ajschmidt8]

currently working through some issues with the release workflow

[ajschmidt8]

I pushed a few more commits to fix the release workflow:

• 22b570f8359ae0833fc660dbb6cfe53deb11ac76
• aead21452aa86e5b62526f6091352c0e1780d0ea
• 54f8ed9631ed8df739cfdba68cab1ffbb0c253e7
• d3dda8adcbb645f19f74f5f0263ea73fbb0da958

The release worked fine after those changes:

• https://github.com/rapidsai/dependency-file-generator/releases/tag/v1.12.1
• https://pypi.org/project/rapids-dependency-file-generator/1.12.1/
• https://anaconda.org/rapidsai/rapids-dependency-file-generator/files?version=1.12.1

Unfortunately a release comment wasn't posted on this PR due to an initial issue in the 1.12.0 release, but I have no reason to believe that PR comments won't work correctly for future releases.

I've also updated the required checks for PRs in this repository.