fix: Solve return type issues with Objectiterator (port of #682)

See #682

src/JsonSchema/Iterator/ObjectIterator.php

@@ -39,6 +39,7 @@ public function __construct($object)
     /**
      * {@inheritdoc}
      */
+    #[\ReturnTypeWillChange]
     public function current()
     {
         $this->initialize();
@@ -49,7 +50,7 @@ public function current()
     /**
      * {@inheritdoc}
      */
-    public function next()
+    public function next(): void
     {
         $this->initialize();
         $this->position++;
@@ -58,7 +59,7 @@ public function next()
     /**
      * {@inheritdoc}
      */
-    public function key()
+    public function key(): int
     {
         $this->initialize();
 
@@ -68,7 +69,7 @@ public function key()
     /**
      * {@inheritdoc}
      */
-    public function valid()
+    public function valid(): bool
     {
         $this->initialize();
 
@@ -78,7 +79,7 @@ public function valid()
     /**
      * {@inheritdoc}
      */
-    public function rewind()
+    public function rewind(): void
     {
         $this->initialize();
         $this->position = 0;
@@ -87,7 +88,7 @@ public function rewind()
     /**
      * {@inheritdoc}
      */
-    public function count()
+    public function count(): int
     {
         $this->initialize();