Remove UTF-8 encoding check in JWEBuilder (#554)

The UTF-8 encoding validation for the payload in the JWEBuilder has been removed. This modification was necessary because the check was unnecessarily restrictive and caused issues in certain use-cases. Now, any string can be used as the payload without throwing an InvalidArgumentException.

src/Library/Encryption/JWEBuilder.php

@@ -132,9 +132,6 @@ public function getCompressionMethodManager(): null|CompressionMethodManager
      */
     public function withPayload(string $payload): self
     {
-        if (mb_detect_encoding($payload, 'UTF-8', true) !== 'UTF-8') {
-            throw new InvalidArgumentException('The payload must be encoded in UTF-8');
-        }
         $clone = clone $this;
         $clone->payload = $payload;