Fails to build with Plasma 6.5, 6.6, and 6.7

[autumn-mck]

Fails to build under Plasma 6.5.0 with the following error:

CMake Error at src/lightlyshaders/CMakeLists.txt:15 (target_link_libraries):
  Target "kwin_effect_lightlyshaders" links to:

    Qt6::CorePrivate

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.



CMake Error at src/lightlyshaders/kcm/CMakeLists.txt:11 (target_link_libraries):
  Target "kwin_lightlyshaders_config" links to:

    Qt6::CorePrivate

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.



CMake Error at src/liblshelper/CMakeLists.txt:15 (target_link_libraries):
  Target "lshelper" links to:

    Qt6::CorePrivate

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

[wxmup]

use this pr can be solved.
#164

[autumn-mck]

fixed for 6.6+ in #166