fix: exact_length does not validate int values

Author: kenjis

system/Validation/StrictRules/Rules.php

@@ -63,6 +63,10 @@ public function equals($str, string $val): bool
      */
     public function exact_length($str, string $val): bool
     {
+        if (is_int($str) || is_float($str)) {
+            $str = (string) $str;
+        }
+
         if (! is_string($str)) {
             return false;
         }