/usr/share/dbconfig-common/dpkg/postinst.sqlite3 is in dbconfig-common 1.8.47+nmu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | dbc_hardcoded_dbtype=sqlite3
. /usr/share/dbconfig-common/dpkg/postinst
|