v6.5.0

Add skip-checkout to base-ref @jamengual (#66)

This pull request includes changes to the `action.yml` file to improve the flexibility and functionality of the GitHub Action configuration. The most important changes include updating the `skip-checkout` input description and default value, modifying the `runs` section to conditionally skip the checkout step, and refining the checkout command for the base ref.

Improvements to input descriptions and defaults:

• action.yml: Updated the skip-checkout input description to include both head-ref and base-ref. Changed the default value of skip-checkout from single to double quotes for consistency.

Enhancements to the runs section:

• action.yml: Added a conditional statement to the actions/checkout@v4 step to skip the checkout if skip-checkout is set to 'true'.
• action.yml: Refined the checkout command for the base ref to conditionally force the checkout based on the skip-checkout input.

Other changes:

• action.yml: Removed an unnecessary blank line in the outputs section.