How do I force a gem file to be installed when the the dependency doesn't match?

I'm building a Jekyll site and I need to be able to convert pages to PDF. I want to use jekyll-pdf but when I include it, bundle tells me it's incompatible:

Because every version of jekyll-pdf depends on jekyll >= 3.1, < 4.A  and Gemfile depends on jekyll ~> 4.3.3,  jekyll-pdf cannot be used.

Looking at the jekyll-pdf repo it seems like it's no longer maintained so I don't expect this to change. Is there a way to force bundle to install that gem even though the dependency isn't valid?