Update dependency prettier to v2

Author: renovate[bot]

package.json

@@ -35,7 +35,7 @@
     "@types/supertest": "2.0.8",
     "jest": "24.8.0",
     "lerna": "3.16.4",
-    "prettier": "1.18.2",
+    "prettier": "2.7.1",
     "supertest": "4.0.2",
     "tslint": "5.18.0",
     "typescript": "^3.7.5"