PR Summary

• Enhanced GitHub Actions Workflow
  We improved the processes in our eBook generation workflow. We updated the workflow name to reflect its purpose more accurately, and enhanced security by using a more advanced version of the library with a token parameter.
• Updated eBook Building Action
  Now using an updated version of the action which allows us to specify PHP version and format options.
• Removal of Obsolete Workflow File
  Eliminated an outdated file (pandoc.yml) that we used to use for generating eBooks, consolidating our processes.
• Additions of CSS Styling Files
  Introduced two new CSS files (highlight.codeblock.min.css and style.css) for enhanced aesthetics. These will help stylize HTML elements and implement syntax highlighting.
• Deletion of YAML Configuration File
  Removed the epub.yml file previously used for generating ePub, as part of our streamlining process.
• Advanced Configurations in PHP file
  Made improvements to our PHP file (ibis.php) which now includes options for custom header styles and cover image settings. This change provides more flexibility and customization when generating eBooks.