fix: allow null for teamer date of birth

src/Entity/Teamer.php

@@ -43,7 +43,7 @@ class Teamer implements TimestampableEntityInterface
     #[Assert\NotBlank(message: 'Bitte gib dein Geschlecht an', groups: ['profile'])]
     private ?string $gender = null;
 
-    #[ORM\Column(type: Types::DATE_IMMUTABLE)]
+    #[ORM\Column(type: Types::DATE_IMMUTABLE, nullable: true)]
     #[Assert\NotNull(message: 'Bitte gib dein Geburtsdatum an', groups: ['profile'])]
     private ?\DateTimeImmutable $dateOfBirth = null;