This involves some explicit adding of gems that were moved out of the default gems:
- `base64` and `csv` are needed for both Jekyll 3.9 and Jekyll 4.3
- `bigdecimal` is just needed for Jekyll 3.9
In the ideal case, this gets backported to both Jekyll 3.9 and 4.3 so we don't need custom Gemfiles. But, I'm also okay with adding these manually for now, and then reverting once both get a backport that patches this. Reminds me of webrick!
This PR essentially updates the "default" Ruby version to 3.3. In the process, it:
- fixes a bug with the linux platform for `sass-embedded`
- regenerates the `Gemfile.lock` with Bundler 2.5.9
- adds Ruby 3.3 to the testing matrix & updates our deployment actions to use Ruby 3.3
- removes Ruby 3.0 from the testing matrix, as it is now end of life
This PR is motivated by https://github.com/just-the-docs/just-the-docs-template/pull/45, where I discovered that depending on the bundler/RubyGems version, the platform resolution for platformed gems can fail.
Ruby 3.2 has stabilized (and the bug with Liquid has been patched). I think this is a good time for us to bump all of our versions, especially with the discussion in #1307.
Separately, I've:
- changed the core test matrix to be across `3.0`, `3.1`, and `3.2`. Ruby 2 has been EOL for ~ 4 months, while 3.0 is around for about 7 more months.
- standardized the formatting of our CI ruby versions to be strings; this is because the number `3.0` gets YAML-casted to `3`
