Add user transformer for projects

app/Transformers/ProjectTransformer.php

@@ -41,8 +41,20 @@ class ProjectTransformer extends EntityTransformer
         'invoices',
         'expenses',
         'quotes',
+        'user',
     ];
 
+    public function includeUser(Project $project): ?Item
+    {
+        $transformer = new UserTransformer($this->serializer);
+
+        if (!$project->user) { //@phpstan-ignore-line
+            return null;
+        }
+
+        return $this->includeItem($project->user, $transformer, User::class);
+    }
+
     public function includeDocuments(Project $project)
     {
         $transformer = new DocumentTransformer($this->serializer);