remove db_name env in database.postgres

[ccpz]

DB_NAME env will create a new database:

https://github.com/sameersbn/docker-postgresql#creating-databases

but src/configure-db.php will only initialize database when database is not exist:

https://github.com/ccpz/Awesome-TTRSS/blob/master/src/configure-db.php#L22

Therefore if db_name exist, it won't initial database schema at first run

[HenryQW]

This comes back to #69 again, DB_NAME is required to get pg_trgm initialized in database.postgres.

I think it's possible to remove:

Awesome-TTRSS/src/configure-db.php

Lines 22 to 31 in 3977459

	if(!dbcheckdb($config)){
	echo 'Database not found, creating.'. PHP_EOL ;
	$pdo = dbconnect($config);
	$pdo -> exec('CREATE DATABASE ' . ($config['DB_NAME']) . ' WITH OWNER ' . ($config['DB_USER']));
	unset($pdo);
	$pdo = dbexist($config);

and get it working.

I'm not a php developer so I'd rather keep it as it is, you are welcome to optimize it.

I've proposed #79 for fixing the issue.