/usr/share/postgresql/10/timezonesets/ is in postgresql-10 10.6-0ubuntu0.18.04.1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/postgresql/10/timezonesets/Africa.txt
/usr/share/postgresql/10/timezonesets/America.txt
/usr/share/postgresql/10/timezonesets/Antarctica.txt
/usr/share/postgresql/10/timezonesets/Asia.txt
/usr/share/postgresql/10/timezonesets/Atlantic.txt
/usr/share/postgresql/10/timezonesets/Australia
/usr/share/postgresql/10/timezonesets/Australia.txt
/usr/share/postgresql/10/timezonesets/Default
/usr/share/postgresql/10/timezonesets/Etc.txt
/usr/share/postgresql/10/timezonesets/Europe.txt
/usr/share/postgresql/10/timezonesets/India
/usr/share/postgresql/10/timezonesets/Indian.txt
/usr/share/postgresql/10/timezonesets/Pacific.txt