Renovate configuration for glotzerlab

To migrate a package from dependabot to Renovate:

• Enable auto-merge in settings.
• Allow squash commits in settings.
• Configure the branch protection rule:
  • Uncheck "Restrict updates".
  • Require 1 approval.
  • Ensure that specific status checks are required.

Then request installation of the Renovate and renovate-approve apps.

On the PR that it creates:

• Remove dependabot.ya?ml.
• If using any uv pip compile files:
  • Modify the headers to use the syntax --python-version={version} (if present).
  • Modify the header to include --output-file={output-file-name}.txt
  • Remove any use of --python-platform.
  • (recommended) Remove any pinning in the .in files. Updates to one dependency at a time often fail to resolve (e.g. the latest nbsphinx does not work with the latest sphinx). We could either pin in .in files and accept many permanently open failing PRs, or unpin in .in files and get the latest full compatible set of packages weekly. The disadvantage to unpinning is that you don't get notification that some dependencies failed to update.
  • Check the renovate logs for the repository and ensure that pip-compile finds the requirements*.txt files and does not report any warnings or errors. These files should also be listed in the PR description.
  • Remove the update-uv-lockfiles action (if used).
• If using any conda lockfiles (see glotzerlab/fresnel#294 for an example):
  • Convert the conda environment.yaml to pixi.toml.
  • Remove environment.yaml and all generated conda lockfiles.
  • Switch from setup-micromamba to setup-pixi in the GitHub Actions workflows.
  • Remove the update-conda-lockfiles action (if used).