community/ruby-pg_query: use postgresql15
Build failed after !52475 (merged)
As https://github.com/pganalyze/pg_query/issues/302 not fixed let's build with 15 to unblock builders
Build failed after !52475 (merged)
As https://github.com/pganalyze/pg_query/issues/302 not fixed let's build with 15 to unblock builders