fix: examples/typescript-ex/package.json to reduce vulnerabilities (cloudevents#395)

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-HOSTEDGITINFO-1088355

Signed-off-by: Lance Ball <[email protected]>

Author: snyk-bot

examples/typescript-ex/package.json

@@ -24,7 +24,7 @@
   },
   "devDependencies": {
     "@types/node": "^14.14.10",
-    "gts": "^1.1.0",
+    "gts": "^3.0.3",
     "typescript": "~4.1.3"
   },
   "dependencies": {