feat: Support php-jwt version 6.0 or higher.

composer.json

@@ -17,7 +17,7 @@
         "php": ">=7.1.0",
         "ext-json": "*",
         "ext-curl": "*",
-        "firebase/php-jwt": "^5.2"
+        "firebase/php-jwt": "^5.2|^6.0"
     },
     "autoload": {
         "psr-4": {