[BUGFIX:BP:11.5] Fix error when indexing pages with field processing …

…instruction categoryUidToHierarchy

Fixes: #3445
Ports: #3446

Classes/FieldProcessor/CategoryUidToHierarchy.php

@@ -80,7 +80,7 @@ public function process(array $values): array
         foreach ($values as $value) {
             $results = array_merge(
                 $results,
-                $this->getSolrRootlineForCategoryId($value)
+                $this->getSolrRootlineForCategoryId((int)$value)
             );
         }