[PostgreSQL] Sylius installation fix

[Rafikooo]

Q	A
Branch?	1.13
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	yes
Related tickets	#15050 #15043 #14950
License	MIT

The installation of Sylius 1.13 with PostgreSQL on board ended with the following error:

This PR resolves this issue

Second, we removed checking:

if (method_exists($connection, 'createSchemaManager')) {
    return $connection->createSchemaManager();
}

if (method_exists($connection, 'getSchemaManager')) {
    /** @psalm-suppress DeprecatedMethod */
    return $connection->getSchemaManager();
}

as we no longer support doctrine/dbal: 2.x in Sylius 1.13

[github-actions]

Bunnyshell Preview Environment deleted

Available commands:

• /bns:deploy to redeploy the environment

[jakubtobiasz]

Thank you, @Rafikooo!