audio/strawberry: Fix qt6 flavor crash upon start

The Qt6 SQL drivers were split out of devel/qt6-base in 0f24404c0a02
and put into databases/qt6-base_sqldriver in fe629e0d7c4b, respectively.
Strawberry needs the sqlite driver to run or will crash upon startup.

For the qt5 flavor, make the sqlite driver a runtime only dependency.
It is not needed for the build.

MFH: 2023Q3