chore: upgrade to latest jekyll and ruby and devcontainer

[jmeridth]

• [x] Have you followed the contributing guidelines?
• [x] Have you explained what your changes do, and why they add value to the Guides?

Please note: we will close your PR without comment if you do not check the boxes above and provide ALL requested information.

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• [x] latest jekyll
• [x] ruby 3.3.5
• [x] devcontainer setup also
  • allows us to work in environment matching prod
  • was getting error locally when trying to run bundle install, this is easier IMO
• [x] update dependabot config for npm
• [x] removed Gemfile.lock from .gitignore so dependabot can actually issue gem updates
• [x] added https://readwrite.com/2014/10/10/open-source-diversity-how-to-contribute/ to html-proofer url_ignores, currently 403ing
  • currently blocking other PRs. Will figure out why after this merges