chore(deps): update dependency @azure/functions to v4

Author: renovate[bot]

package.json

@@ -14,7 +14,7 @@
     "@probot/adapter-azure-functions": "^1.0.23"
   },
   "devDependencies": {
-    "@azure/functions": "^3.2.0",
+    "@azure/functions": "^4.0.0",
     "nock": "^13.2.8",
     "smee-client": "^1.2.3",
     "uvu": "^0.5.6"