Update dependency jsonwebtoken to v8.4.0

Author: renovate[bot]

iot/http_example/package.json

@@ -9,7 +9,7 @@
     "test": "repo-tools test run --cmd ava -- -T 3m --verbose system-test/*.test.js"
   },
   "dependencies": {
-    "jsonwebtoken": "7.4.1",
+    "jsonwebtoken": "8.4.0",
     "retry-request": "3.3.1",
     "yargs": "8.0.2"
   },

iot/mqtt_example/package.json

@@ -9,7 +9,7 @@
     "test": "repo-tools test run --cmd ava -- -T 3m --verbose system-test/*.test.js"
   },
   "dependencies": {
-    "jsonwebtoken": "8.2.0",
+    "jsonwebtoken": "8.4.0",
     "mqtt": "2.16.0",
     "yargs": "11.0.0"
   },