Fix password validation min length message

When relying on static config instead of an explicitly set minLength then this message would show without the value, like "it must be  or more characters long".

src/Security/PasswordValidator.php

@@ -236,7 +236,7 @@ class PasswordValidator
             $error = _t(
                 __CLASS__ . '.TOOSHORT',
                 'Password is too short, it must be {minimum} or more characters long',
-                ['minimum' => $this->minLength]
+                ['minimum' => $minLength]
             );
 
             $valid->addError($error, 'bad', 'TOO_SHORT');