Fix import XML data with leading zeros

Pull-request: #14944
Signed-off-by: William Desportes <williamdes@wdes.fr>

libraries/classes/Import.php

@@ -814,6 +814,10 @@ class Import
             return self::BIGINT;
         }
 
+        if ($cell !== (string)(int)$cell) {
+            return self::VARCHAR;
+        }
+
         return self::INT;
     }