Add psalm to CI

[franmomu]

this PR adds psalm at level 7 and fixes the issues found, symfony/validator and symfony/security-bundle have been added because they are used:

https://github.com/doctrine/DoctrineMongoDBBundle/blob/baddc63a027d2ef363359a6d527a2670512b8e8b/Tests/DependencyInjection/AbstractMongoDBExtensionTest.php#L25

which has a dependency on https://github.com/symfony/doctrine-bridge/blob/ed2e5a8a0987e6484ffac544918e1bd3da7ffb1c/Validator/Constraints/UniqueEntityValidator.php#L15-L18

https://github.com/doctrine/DoctrineMongoDBBundle/blob/baddc63a027d2ef363359a6d527a2670512b8e8b/Validator/Constraints/Unique.php#L7

depends on https://github.com/symfony/doctrine-bridge/blob/ed2e5a8a0987e6484ffac544918e1bd3da7ffb1c/Validator/Constraints/UniqueEntity.php#L14

And for security, we are using:

https://github.com/doctrine/DoctrineMongoDBBundle/blob/8db802c4d49ae63eef1a4a6b62eb8578391ed4a7/Tests/Fixtures/Security/User.php#L9

https://github.com/doctrine/DoctrineMongoDBBundle/blob/8db802c4d49ae63eef1a4a6b62eb8578391ed4a7/DoctrineMongoDBBundle.php#L16

which depends on https://github.com/symfony/doctrine-bridge/blob/ed2e5a8a0987e6484ffac544918e1bd3da7ffb1c/DependencyInjection/Security/UserProvider/EntityFactory.php#L14

[malarzm]

Awesome, thank you @franmomu!