minidlna: Implement force_upgrade
The media_dir setting may be changed, which leads to a prompt when upgrading from 1.2.1+dfsg-1+b1 to 1.2.1+dfsg-2+deb10u2 (or later).
The media_dir setting may be changed, which leads to a prompt when upgrading from 1.2.1+dfsg-1+b1 to 1.2.1+dfsg-2+deb10u2 (or later).