Fix build by lowering KDE_COMPILERSETTINGS_LEVEL

It doesn't build against the stricter 5.85 level

CMakeLists.txt

@@ -6,6 +6,7 @@ project (KActivityManagerd)
 
 set (QT_MIN_VERSION "5.15.0")
 set (KF5_MIN_VERSION "5.86")
+set (KDE_COMPILERSETTINGS_LEVEL "5.82")
 set (Boost_MINIMUM_VERSION "1.58")
 
 # We don't build in-source