Fix some phpdoc

[franmomu]

Q	A
Type	improvement
BC Break	no
Fixed issues

Summary

Raising psalm level locally and analyzing tests directory made some issues appear:

ReplaceRoot allowing Expr:

mongodb-odm/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/ReplaceRootTest.php

Lines 45 to 49 in f225a0c

	->replaceRoot(
	$builder->expr()
	->field('isToday')
	->eq('$createdAt', $dateTime)
	);

Bucket::groupBy allowing string:

mongodb-odm/tests/Doctrine/ODM/MongoDB/Tests/Aggregation/Stage/BucketTest.php

Lines 20 to 22 in f225a0c

	$bucketStage = new Bucket($this->getTestAggregationBuilder(), $this->dm, new ClassMetadata(User::class));
	$bucketStage
	->groupBy('$someField')

With ClassMetadata I was getting:

ERROR: InvalidArgument - tests/Doctrine/ODM/MongoDB/Tests/QueryTest.php:418:30 - Argument 2 of Doctrine\ODM\MongoDB\Query\Query::__construct expects Doctrine\ODM\MongoDB\Mapping\ClassMetadata<object>, Doctrine\ODM\MongoDB\Mapping\ClassMetadata<Documents\User> provided (see https://psalm.dev/004)
        new Query($this->dm, new ClassMetadata(User::class), $this->getMockCollection(), ['type' => -1], []);

Making it covariant I think it makes sense as it is in doctrine/persistence.

[malarzm]

Thanks @franmomu!