Use KDECompilerSettings, kf5.85 defines CMAKE_CXX_STANDARD 17 directly

CMakeLists.txt

@@ -14,9 +14,6 @@ project(elisa
     VERSION ${RELEASE_SERVICE_VERSION}
     LANGUAGES CXX)
 
-set(CMAKE_CXX_STANDARD_REQUIRED ON)
-set(CMAKE_CXX_STANDARD 17)
-
 set(REQUIRED_QT_VERSION "5.15.0")
 find_package(Qt5 ${REQUIRED_QT_VERSION} CONFIG REQUIRED Core Network Qml Quick Test Sql Multimedia Svg Gui Widgets QuickTest Concurrent QuickControls2)
 
@@ -29,7 +26,7 @@ set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake" ${ECM_MODULE_PATH})
 
 include(KDEInstallDirs)
 include(KDECMakeSettings)
-include(KDEFrameworkCompilerSettings NO_POLICY_SCOPE)
+include(KDECompilerSettings NO_POLICY_SCOPE)
 include(ECMInstallIcons)
 include(FeatureSummary)
 include(ECMAddAppIcon)