update infrastructure

[rcannood]

Describe your changes

• Update R packages
• Remove Python from list of dependencies
• Update Quarto
• Fixes to styling
• Simplify footer
• Update openproblems-v2 submodule

Checklist before requesting a review

• [x] I have performed a self-review of my code

• Check the correct box. Does this PR contain:

  • [ ] Breaking changes
  • [ ] New functionality
  • [ ] Major changes
  • [x] Minor changes
  • [ ] Bug fixes

• [x] Proposed changes are described in the CHANGELOG.md

• [x] CI Preview succeeds and looks good!

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