Update dependency prettier to v2.6.0

Author: renovate-bot

package-lock.json

@@ -46,7 +46,7 @@
     "cross-env": "7.0.3",
     "jest": "26.6.3",
     "nodemon": "2.0.15",
-    "prettier": "2.5.1",
+    "prettier": "2.6.0",
     "subscriptions-transport-ws": "0.11.0",
     "supertest": "6.2.2",
     "ts-jest": "26.5.6",