Add PgBouncer as image option
Gitaly project plans to use PgBouncer for Praefect service gitaly#2816 (closed) We want to have an image for CI so we can test interaction of Praefect with PostgreSQL database if PgBouncer sits in between.
Installation script added with 1.14.0 version of PgBouncer (latest).
Related to: gitaly#2816 (closed)
Edited by Zeger-Jan van de Weg