Add support for new ruby & jekyll version

Purpose

The purpose of this PR is to fix #69

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[x] I have read and understood the development best practices guidelines
[x] My code follows the style guidelines of this project
[x] I have performed a self-review of my own code
[x] I have commented my code, particularly in hard-to-understand areas
[ ] I have made corresponding changes to the documentation

## Test environment ## Learning