[sqlite3] Change db locking mode to DEFAULT.
[sqlite3] Change db locking mode to DEFAULT.

EXCLUSIVE locking with combination with the dnf.comps.CompsQuery fix
caused crashes in dnf unit tests. More restrictive locking mode
seems to be fixing the issue.

hughsie/libhif,rpm-software-management/libhif,Conan-Kudo/libhif,Conan-Kudo/libhif,hughsie/libhif,rpm-software-management/libdnf,rpm-software-management/libdnf,rpm-software-management/libhif,rpm-software-management/libdnf,hughsie/libhif,Conan-Kudo/libhif,rpm-software-management/libhif,rpm-software-management/libhif,Conan-Kudo/libhif,hughsie/libhif,rpm-software-management/libdnf