Help with setting up discourse An error occurred while installing xorcist (1.1.2), and Bundler cannot continue

When I do bundle install I get this error: An error occurred while installing xorcist (1.1.2), and Bundler cannot continue.

Can someone help.

Here is the docs Im following currently:

here is the full error if that helps.

In Gemfile:
  unf was resolved to 0.1.4, which depends on
    unf_ext


Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /var/lib/gems/2.7.0/gems/xorcist-1.1.2/ext/xorcist
/usr/bin/ruby2.7 -I /usr/lib/ruby/2.7.0 -r ./siteconf20211120-12641-1468e8.rb extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h

You might have to install separate package for the ruby development
environment, ruby-dev or ruby-devel for example.

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.7.0/gems/xorcist-1.1.2 for inspection.
Results logged to /var/lib/gems/2.7.0/extensions/x86_64-linux/2.7.0/xorcist-1.1.2/gem_make.out

  /usr/lib/ruby/2.7.0/rubygems/ext/builder.rb:97:in `run'
  /usr/lib/ruby/2.7.0/rubygems/ext/ext_conf_builder.rb:48:in `block in build'
  /usr/lib/ruby/2.7.0/tempfile.rb:291:in `open'
  /usr/lib/ruby/2.7.0/rubygems/ext/ext_conf_builder.rb:30:in `build'
  /usr/lib/ruby/2.7.0/rubygems/ext/builder.rb:167:in `block in build_extension'
  /usr/lib/ruby/2.7.0/rubygems/ext/builder.rb:163:in `synchronize'
  /usr/lib/ruby/2.7.0/rubygems/ext/builder.rb:163:in `build_extension'
  /usr/lib/ruby/2.7.0/rubygems/ext/builder.rb:208:in `block in build_extensions'
  /usr/lib/ruby/2.7.0/rubygems/ext/builder.rb:205:in `each'
  /usr/lib/ruby/2.7.0/rubygems/ext/builder.rb:205:in `build_extensions'
  /usr/lib/ruby/2.7.0/rubygems/installer.rb:844:in `build_extensions'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/rubygems_gem_installer.rb:71:in `build_extensions'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/rubygems_gem_installer.rb:28:in `install'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/source/rubygems.rb:200:in `install'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/installer/gem_installer.rb:54:in `install'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/installer/gem_installer.rb:16:in `install_from_spec'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/installer/parallel_installer.rb:186:in `do_install'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/installer/parallel_installer.rb:177:in `block in worker_pool'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/worker.rb:62:in `apply_func'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/worker.rb:57:in `block in process_queue'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/worker.rb:54:in `loop'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/worker.rb:54:in `process_queue'
  /var/lib/gems/2.7.0/gems/bundler-2.2.31/lib/bundler/worker.rb:91:in `block (2 levels) in create_threads'

An error occurred while installing xorcist (1.1.2), and Bundler cannot continue.

In Gemfile:
  xorcist