Outdated theme?

Hi all, trying to test out a theme but when I run jekyll serve I get the following:
Traceback (most recent call last):
12: from /home/chris/.rbenv/versions/2.7.2/bin/jekyll:23:in <main>' 11: from /home/chris/.rbenv/versions/2.7.2/bin/jekyll:23:in load’
10: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/jekyll-4.1.1/exe/jekyll:11:in <top (required)>' 9: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/gems/2.7.0/gems/jekyll-4.1.1/lib/jekyll/plugin_manager.rb:52:in require_from_bundler’
8: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler.rb:149:in setup' 7: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler/runtime.rb:20:in setup’
6: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler/runtime.rb:101:in block in definition_method' 5: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler/definition.rb:226:in requested_specs’
4: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler/definition.rb:237:in specs_for' 3: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler/definition.rb:170:in specs’
2: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler/spec_set.rb:80:in materialize' 1: from /home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler/spec_set.rb:80:in map!’
/home/chris/.rbenv/versions/2.7.2/lib/ruby/2.7.0/bundler/spec_set.rb:86:in `block in materialize’: Could not find public_suffix-4.0.1 in any of the sources (Bundler::GemNotFound)

Any suggestions on a way to fix it?

The clue is in the above error message.
You are missing some dependencies.
Try running bundle install to install missing gems.

Thanks Ashmaroli, turned out my Bundler itself was out of date.