Update PostgreSQLContainer.java

[zapp88]

This a fix for bug #10176

[zapp88]

Or, if the proposed bug fix is not acceptable, a more robust approach would be to change the waitStrategy to:

new ShellStrategy().withCommand("pg_isready -U postgres");

[eddumelendez]

Thanks for your contribution, @zapp88.

1. The suggested approach is not considering that empty database start the postgres service twice. See the link I left in the duplicated issue.
2. The successful command is not reliable because of the restart of the engine, sooner or later will fail. We have explored that way too.