title: Can't connect postgres_exporter to postgresql database
body: <p>I can't connect <a href="https://github.com/wrouesnel/postgres_exporter" rel="nofollow noreferrer">postgres_exporter</a> to postgresql database. I am getting </p>
  
  <pre><code>time="2019-04-29T15:37:46Z" level=info msg="Established new database connection to \"localhost:5432\"." source="postgres_exporter.go:767"
  time="2019-04-29T15:37:46Z" level=error msg="Error opening connection to database (postgresql://postgres:PASSWORD_REMOVED@localhost:5432/postgres?sslmode=disable): pq: unknown authentication response: 10" source="postgres_exporter.go:1260"
  time="2019-04-29T15:37:46Z" level=info msg="Starting Server: :9187" source="postgres_exporter.go:1360"
  </code></pre>
  
  <p>Port is ok, password too. When I am trying to run it as </p>
  
  <pre><code># Start an example database
  docker run --net=host -it --rm -e POSTGRES_PASSWORD=password postgres
  # Connect to it
  docker run --net=host -e DATA_SOURCE_NAME="postgresql://postgres:password@localhost:5432/postgres?sslmode=disable" wrouesnel/postgres_exporter
  
  </code></pre>
  
  <p>it works perfectly but there is already postgresql running instance so I can't create new one.</p>