Added explicit libyajl2 >= 2.1 dependency to allow ffi-yajl 2.7.7 installation

[nikhil2611]

Description

This resolves bundler conflicts where older libyajl2 1.2.0 prevented newer ffi-yajl versions

• Upgrading to libyajl2 >= 2.1 allows ffi-yajl to upgrade to 2.7.7, which requires the newer libyajl2 version

Related Issue

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (non-breaking change that does not add functionality or fix an issue)

Checklist:

• I have read the CONTRIBUTING document.
• I have run the pre-merge tests locally and they pass.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• If Gemfile.lock has changed, I have used --conservative to do it and included the full output in the Description above.
• All new and existing tests passed.
• All commits have been signed-off for the Developer Certificate of Origin.