fix: add missing dependency for building on fedora

[kada49]

This adds a missing dependency for building on Fedora 41. Without this package I got the following cmake error:

-- Configuring done (1.0s)
CMake Error in src/CMakeLists.txt:
  Imported target "Qt6::WidgetsPrivate" includes non-existent path

    "/usr/include/qt6/QtWidgets/6.8.0"

  in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:

  * The path was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and references files it does not
  provide.



CMake Error in src/CMakeLists.txt:
  Imported target "Qt6::WidgetsPrivate" includes non-existent path

    "/usr/include/qt6/QtWidgets/6.8.0"

  in its INTERFACE_INCLUDE_DIRECTORIES.  Possible reasons include:

  * The path was deleted, renamed, or moved to another location.

  * An install or uninstall procedure did not complete successfully.

  * The installation package was faulty and references files it does not
  provide.



-- Generating done (0.1s)
CMake Generate step failed.  Build files cannot be regenerated correctly.

This error does not pop up and cmake configures correctly if qt6-qtbase-private-devel is installed.

[CLAassistant]

All committers have signed the CLA.

[Nerixyz]

Thank you!