Upgrading ruby and jekyll versions

[ZoeLeBlanc]

A much needed upgrade for Ruby and Jekyll versions so that it can run on newer Macbooks. Also upgrading our build.yml to use the official htmlproofer now that we have upgraded everything. This is part of the tasks for #3497

Checklist

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[ZoeLeBlanc]

Ok so I've had to add in this logic to the bundle file to ensure that GitHub build.yml workflow works:

bundle lock --add-platform x86_64-linux
bundle lock --add-platform arm64-darwin-24
bundle lock --add-platform x86_64-darwin-20
bundle lock --add-platform x64-mingw32

This gives us the following

Platform	Use Case
x86_64-linux	GitHub Actions, most Linux distros
arm64-darwin-24	Apple Silicon (M1/M2 Macs)
x86_64-darwin-20	Intel Macs
x64-mingw32	Windows users with RubyInstaller

I've also had to add in logic for pulling out htmlproofer errors. To do it you run:

bundle exec htmlproofer _site > htmlproofer-output.txt 2>&1

ruby parse_htmlproofer_to_csv.rb

Will be working with @anisa-hawes this month to fix these