fix function return type

Author: maslii

lib/internal/Magento/Framework/Data/Collection.php

@@ -259,7 +259,7 @@ public function getLastPageNumber()
         if (0 === $collectionSize) {
             return 1;
         } elseif ($this->_pageSize) {
-            return ceil($collectionSize / $this->_pageSize);
+            return (int)ceil($collectionSize / $this->_pageSize);
         } else {
             return 1;
         }