Change string type back to mixed from automatic psalm fix

Author: Harm-r

src/Controllers/VerifiableCredentials/CredentialIssuerCredentialController.php

@@ -839,7 +839,7 @@ public function credential(Request $request): Response
      * @psalm-suppress UnusedVariable, MixedAssignment
      * @param array-key[] $path
      */
-    protected function setCredentialClaimValue(array &$claims, array $path, string $value): void
+    protected function setCredentialClaimValue(array &$claims, array $path, mixed $value): void
     {
         $temp = &$claims;