Add faraday-retry to Gemfile

[bastelfreak]

It's an optional dependency of octokit. Without it we always get a warning on the CLI:

To use retry middleware with Faraday v2.0+, install `faraday-retry` gem

[evgeni]

But we're not using octokit, so why pulling in another dep?

[bastelfreak]

octokit is a dependency of github-pages-health-check, jekyll-gist and jekyll-github-metadata. octokit by default uses faraday which in turn wants to use faraday-retry and complains when it's missing. It's a bit of a rabbithole :( At Vox Pupuli we've the same issue with the github_changelog_generator that also pulls in octokit => faraday => faraday-retry. That's why we added faraday-retry there as well.

[evgeni]

I know. But we're still not actively using any of that, so I see no reason to add another dependency just to silence that warning.