NEXT-00000 Fix: failing assert in bin/console state-machine:dump

```
bin/console state-machine:dump order.state
```

fails

assert(\is_string($v))

Because there is a 'label' => null entry in the options array.

Co-authored-by: cyl3x <[email protected]>

Author: amenk

changelog/_unreleased/2024-12-06-fix-assert-in-state-machine-dump.md

@@ -0,0 +1,9 @@
+---
+title: Fix assert `bin/console state-machine:dump`
+issue: NEXT-00000
+author: Alexander Menk
+author_email: [email protected]
+author_github: amenk
+---
+# Core
+* Changed assert in `bin/console state-machine:dump`. 

src/Core/System/StateMachine/Util/StateMachineGraphvizDumper.php

@@ -172,8 +172,10 @@ private function addOptions(array $options): string
         $code = [];
         foreach ($options as $k => $v) {
             \assert(\is_string($k));
-            \assert(\is_string($v));
-            $code[] = \sprintf('%s="%s"', $k, $v);
+            if ($v !== null) {
+                \assert(\is_scalar($v) || $v instanceof \Stringable);
+                $code[] = \sprintf('%s="%s"', $k, $v);
+            }
         }
 
         return implode(' ', $code);