Add version.rb file to make compatible with release GitHub Action

[parkr]

The release GitHub Action looks for changes to a version.rb file. We don't have one of those in this repo, so it will never run.

Noted by @ashmaroli here: #30 (comment)

[ashmaroli]

Hello @parkr,
It looks like Jekyllbot has not been configured to publish the cut gem as per this workflow log.

(API_KEY Environment Variable missing in repo settings).

I have deleted the GitHub Tag and Release to facilitate a smooth workflow rerun.

[parkr]

@ashmaroli Added! It's RUBYGEMS_GEM_PUSH_API_KEY and should now be exposed to this repo.

[ashmaroli]

Thanks @parkr, will you be able to rerun the linked release workflow? I am not able to do so at the moment.
(Thanks in advance.)

Update: I have rerun the workflow and published v0.14.