v1.1.5

- Changed the temporary directory path to user's cache directory, which is more appropriate for storing cache files and avoids issues with unintended cleanup.
- Fixed the isssue where extra metadata information was not being saved to M4B files when they have no chapters, ensuring that all metadata is correctly written to the output file.
- Fixed sleep prevention process not ending if program exited using Ctrl+C or kill.
- Improved automatic filename suffixing to better prevent overwriting files with the same name, even if they have different extensions.
- Improvements in code and documentation.