Update INSTALL.md

[fluent-themes]

Summary

Related Issues

Type of Change

• Bug fix (non-breaking change)
• New feature (non-breaking change)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Changes Made

Testing

Testing in Mock Mode

Manual Testing

Screenshots

Breaking Changes

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published