v1.3.0 Qt 6.8

[mxrcode]

This pull request includes several updates to the TaskGuard project, focusing on version updates, UI improvements, and code refactoring for better maintainability and functionality. Below are the most important changes:

Code Refactoring:

• Refactored the on_task_item_clicked method in mainwindow.cpp to improve readability and functionality, including the introduction of new methods for auto-saving task data.
• Renamed and added new methods in mainwindow.h to support the refactoring changes.

Version Updates:

• Updated the project version to 1.3.0 in CMakeLists.txt and src/version.h. [1] [2]
• Updated the Qt version used in the about_qt_window.ui file from 6.4.3 to 6.8.

UI and Documentation:

• Updated the copyright year to 2024 in the about_qt_window.ui file.
• Corrected the encryption plugin link in the README.md file.

Logging:

• Enhanced log message formatting in main.cpp by adding brackets around the timestamp.