Disable jekyll on github actions

[blurfx]

What this PR does / why we need it?

Prevent examples from being built with Jekyll. Next.js-based examples can't load css and js assets when built with Jekyll.

Any background context you want to provide?

Relative PR: yorkie-team/yorkie-team.github.io#106

What are the relevant tickets?

Fixes #673

Checklist

• Added relevant tests or not required
• Didn't break anything

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (7baa69f) 67.89% compared to head (7eef768) 67.83%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #674      +/-   ##
==========================================
- Coverage   67.89%   67.83%   -0.06%     
==========================================
  Files          58       58              
  Lines        8734     8734              
  Branches      784      784              
==========================================
- Hits         5930     5925       -5     
- Misses       2546     2550       +4     
- Partials      258      259       +1     

see 1 file with indirect coverage changes

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[hackerwins]

Thanks for your contribution.