fix build with qt 6.10

https://github.com/qgis/QGIS/pull/64056

Index: external/qspatialite/CMakeLists.txt
--- external/qspatialite/CMakeLists.txt.orig
+++ external/qspatialite/CMakeLists.txt
@@ -5,6 +5,7 @@ add_definitions(${QT_DEFINITIONS})
 add_definitions(-DQT_PLUGIN)
 add_definitions(-DQT_SHARED)
 
+find_package(${QT_VERSION_BASE}Sql CONFIG)
 include_directories(SYSTEM ${${QT_VERSION_BASE}Sql_PRIVATE_INCLUDE_DIRS})
 
 set(QSQLSPATIALITE_SRC qsql_spatialite.cpp smain.cpp qsql_spatialite.h smain.h)
