/usr/lib/ is in lua-sql-postgres 2.3.4-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/liblua5.1-sql-postgres.so.2.0.0
/usr/lib/x86_64-linux-gnu/liblua5.2-sql-postgres.so.2.0.0
/usr/lib/x86_64-linux-gnu/liblua5.3-sql-postgres.so.2.0.0
/usr/lib/x86_64-linux-gnu/lua/
/usr/lib/x86_64-linux-gnu/lua/5.1/
/usr/lib/x86_64-linux-gnu/lua/5.1/luasql/
/usr/lib/x86_64-linux-gnu/lua/5.2/
/usr/lib/x86_64-linux-gnu/lua/5.2/luasql/
/usr/lib/x86_64-linux-gnu/lua/5.3/
/usr/lib/x86_64-linux-gnu/lua/5.3/luasql/
/usr/lib/x86_64-linux-gnu/liblua5.1-sql-postgres.so.2
/usr/lib/x86_64-linux-gnu/liblua5.2-sql-postgres.so.2
/usr/lib/x86_64-linux-gnu/liblua5.3-sql-postgres.so.2
/usr/lib/x86_64-linux-gnu/lua/5.1/luasql/postgres.so
/usr/lib/x86_64-linux-gnu/lua/5.2/luasql/postgres.so
/usr/lib/x86_64-linux-gnu/lua/5.3/luasql/postgres.so