Restore psalm-external-mutation-free annotations

Although I could not find a PHPStan equivalent, these could still be
useful for end users and should not be removed in a patch release.

src/Persistence/Reflection/EnumReflectionProperty.php

@@ -32,16 +32,31 @@ public function __construct(ReflectionProperty $originalReflectionProperty, stri
         $this->enumType                   = $enumType;
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @psalm-external-mutation-free
+     */
     public function getDeclaringClass(): ReflectionClass
     {
         return $this->originalReflectionProperty->getDeclaringClass();
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @psalm-external-mutation-free
+     */
     public function getName(): string
     {
         return $this->originalReflectionProperty->getName();
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @psalm-external-mutation-free
+     */
     public function getType(): ?ReflectionType
     {
         return $this->originalReflectionProperty->getType();
@@ -134,16 +149,31 @@ private function toEnum($value)
         return $this->enumType::from($value);
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @psalm-external-mutation-free
+     */
     public function getModifiers(): int
     {
         return $this->originalReflectionProperty->getModifiers();
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @psalm-external-mutation-free
+     */
     public function getDocComment(): string|false
     {
         return $this->originalReflectionProperty->getDocComment();
     }
 
+    /**
+     * {@inheritDoc}
+     *
+     * @psalm-external-mutation-free
+     */
     public function isPrivate(): bool
     {
         return $this->originalReflectionProperty->isPrivate();