fix: upgrade prettier from 1.18.2 to 1.19.1

Snyk has created this PR to upgrade prettier from 1.18.2 to 1.19.1.

See this package in NPM:
https://www.npmjs.com/package/prettier

See this project in Snyk:
https://app.snyk.io/org/bluewallet/project/29c066bc-abce-44d9-b68e-064466e610e7?utm_source=github&utm_medium=upgrade-pr

package.json

@@ -32,7 +32,7 @@
     "morgan": "^1.9.1",
     "mustache": "^3.0.1",
     "node-uuid": "^1.4.8",
-    "prettier": "^1.15.3",
+    "prettier": "^1.19.1",
     "request": "^2.88.0",
     "request-promise": "^4.2.2",
     "winston": "^3.1.0"