fix: appengine/sendgrid/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-AXIOS-9292519

Author: snyk-bot

appengine/sendgrid/package.json

@@ -16,7 +16,7 @@
     "body-parser": "^1.19.0",
     "express": "^4.16.4",
     "pug": "^3.0.0",
-    "@sendgrid/client": "^7.0.0"
+    "@sendgrid/client": "^8.1.5"
   },
   "devDependencies": {
     "mocha": "^9.1.2",