ZEPPELIN-1554: Upgrade jekyll

[epugh]

What is this PR for?

I wanted to generate the docs site on my Mac, and found a bunch of old dependencies that needed updating. I don't know if this is related to ZEPPELIN-1554, which looks like there was some good work that is similar to what I've done.

If you want, I could pull in some of the other fixes done in #1577 in other PR's...

First time? Check out the contributing guide - https://zeppelin.apache.org/contribution/contributions.html

What type of PR is it?

Bug Fix - I think this is right since we need updates to run Jekyll.

Todos

• - Task

What is the Jira issue?

https://issues.apache.org/jira/browse/ZEPPELIN-1554

How should this be tested?

• Strongly recommended: add automated unit tests for any new or changed behavior
• Outline any manual steps to test the PR here.
• I ran the bundle exec jekyll serve --watch command.

Screenshots (if appropriate)

Questions:

• Does the licenses files need update? No
• Is there breaking changes for older versions? No
• Does this needs documentation? No

[zjffdu]

@epugh Sorry, I forgot to mention that you can check the README.md for how to generate docs. Building docs via docker would be very easy.

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This pull request has been inactive for over a year. If no further activity occurs within the next 30 days, it will be automatically closed. If you believe this PR is still relevant, please feel free to leave a comment or make an update. Thank you!

[github-actions]

This pull request has been automatically closed due to prolonged inactivity (over one year without updates). If you feel this was done in error or would like to continue the discussion, feel free to reopen it. Thank you for your contributions!