Update dependency loopback to v3.24.0

Author: renovate[bot]

appengine/loopback/package.json

@@ -22,7 +22,7 @@
  "serve-favicon": "2.4.5",
  "strong-error-handler": "2.3.2",
  "loopback-datasource-juggler": "3.28.0",
- "loopback": "3.18.2"
+ "loopback": "3.24.0"
  },
  "devDependencies": {
  "@google-cloud/nodejs-repo-tools": "^2.3.5"