Mitgliedsantrag Sheet base64 encode binary signature

static/mitgliedsantrag.php

@@ -110,7 +110,7 @@ $pkey = openssl_pkey_get_private(base64_decode(getenv('MITGLIEDSANTRAG_SHEET_PKE
 $jwt_signature = '';
 openssl_sign($jwt_header.'.'.$jwt_payload, $jwt_signature, $pkey, OPENSSL_ALGO_SHA256);
 openssl_free_key($pkey);
-$jwt_signature = str_replace(['+', '/', '='], ['-', '_', ''], $jwt_signature);
+$jwt_signature = str_replace(['+', '/', '='], ['-', '_', ''], base64_encode($jwt_signature));
 $req_body = <<<EOF
 {
     "grant_type": "urn:ietf:params:oauth:grant-type:jwt-bearer",