Fix PostgreSQL install (#2735)
Fix PostgreSQL install (#2735)

* Fix PostgreSQL install

Fix https://github.com/FreshRSS/FreshRSS/issues/2732
When username is different from database name

* Add more comments

https://github.com/FreshRSS/FreshRSS/pull/2735/files/2b7807d1b3fdd0dc34538faad465934fb737fa3a#r361846714

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