/usr/lib/tmpfiles.d/opendnssec-signer.conf is in opendnssec-signer 1:2.1.3-0.2build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1
d /run/opendnssec 0775 opendnssec opendnssec - -