Fix reference error in PostgresEventStore for MetadataMatcher with IN Operations.
Fix reference error in PostgresEventStore for MetadataMatcher with IN Operations.

The removed value reference leads to wrong values for the IN operation.

Example:

```
(new MetadataMatcher())
	->withMetadataMatch(
	    'event_name',
	    Operator::IN(),
	    [
	        'Event-1',
	        'Event-2'
	    ],
	    FieldType::MESSAGE_PROPERTY()
	)
```

Results to:

```
$values = [
	'metadata_0_0' => 'Event-1',
	'metadata_0_1' => 'Event-1'
]
```

The Second values is replaced by the value reference with the first one.

prooph/pdo-event-store