fix: packages/service/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-DOTQS-8709975

Author: snyk-bot

packages/service/package.json

@@ -40,7 +40,7 @@
     "gulp": "^4.0.2",
     "mocha-junit-reporter": "^2.0.2",
     "proxyquire": "^2.1.3",
-    "serverless": "^2.72.3",
+    "serverless": "^3.0.0",
     "serverless-domain-manager": "^6.0.3",
     "serverless-dynamodb-local": "^0.2.40",
     "serverless-offline": "^8.7.0",