Can't install jekyll on linux mint 20.1

Hi, I’m having trouble installing jekyll on Linux Mint 20.1

I am following the ubuntu install instructions
All the prerequisites report as installed.
Because I am using zsh, I added the lines configuring the gem path to ~/.zshrc
When I run gem install jekyll bundler, I get the following error:

ERROR:  Error installing jekyll:
	The last version of sass-embedded (~> 1.54) to support your Ruby & RubyGems was 1.57.1. Try installing it with `gem install sass-embedded -v 1.57.1` and then running the current command again
	sass-embedded requires RubyGems version >= 3.3.22. The current RubyGems version is 3.1.2. Try 'gem update --system' to update RubyGems itself.
Successfully installed bundler-2.4.4
Parsing documentation for bundler-2.4.4
Done installing documentation for bundler after 0 seconds
1 gem installed

Running gem update --system gives the following error:

Updating rubygems-update
Successfully installed rubygems-update-3.4.4
Parsing documentation for rubygems-update-3.4.4
Done installing documentation for rubygems-update after 0 seconds
Parsing documentation for rubygems-update-3.4.4
Done installing documentation for rubygems-update after 0 seconds
Installing RubyGems 3.4.4
Traceback (most recent call last):
	5: from setup.rb:22:in `<main>'
	4: from setup.rb:22:in `require'
	3: from /home/sam/gems/gems/rubygems-update-3.4.4/lib/rubygems.rb:1322:in `<top (required)>'
	2: from /home/sam/gems/gems/rubygems-update-3.4.4/lib/rubygems.rb:1322:in `require'
	1: from /usr/lib/ruby/vendor_ruby/rubygems/defaults/operating_system.rb:49:in `<top (required)>'
/usr/lib/ruby/vendor_ruby/rubygems/defaults/operating_system.rb:50:in `<class:Specification>': undefined method `rubyforge_project=' for class `Gem::Specification' (NameError)
	3: from setup.rb:22:in `<main>'
	2: from setup.rb:22:in `require'
	1: from /home/sam/gems/gems/rubygems-update-3.4.4/lib/rubygems.rb:1318:in `<top (required)>'
/home/sam/gems/gems/rubygems-update-3.4.4/lib/rubygems.rb:1332:in `rescue in <top (required)>': undefined method `rubyforge_project=' for class `Gem::Specification' (NameError)
Loading the /usr/lib/ruby/vendor_ruby/rubygems/defaults/operating_system.rb file caused an error. This file is owned by your OS, not by rubygems upstream. Please find out which OS package this file belongs to and follow the guidelines from your OS to report the problem and ask for help.

Can anybody here help?

Hello @SamMiddleton,
Try running the following instead:

ruby --version
gem install jekyll --version="~> 4.2.0"