Remove length test

The regex already covers this

Author: tvdijen

src/Base64Trait.php

@@ -10,7 +10,6 @@
 use function base64_encode;
 use function filter_var;
 use function sprintf;
-use function strlen;
 
 /**
  * @package simplesamlphp/assert
@@ -43,8 +42,6 @@ protected static function validBase64(string $value, string $message = ''): void
 
         if (filter_var($value, FILTER_VALIDATE_REGEXP, ['options' => ['regexp' => self::$base64_regex]]) === false) {
             $result = false;
-        } elseif (strlen($value) % 4 !== 0) {
-            $result = false;
         } else {
             $decoded = base64_decode($value, true);
             if (empty($decoded)) { // Invalid _or_ empty string