chore: release 2.2.1 (#159)

Author: release-please[bot]

security-center/snippets/package.json

@@ -9,7 +9,7 @@
   },
   "license": "Apache-2.0",
   "dependencies": {
-    "@google-cloud/security-center": "^2.1.0"
+    "@google-cloud/security-center": "^2.2.1"
   },
   "devDependencies": {
     "chai": "^4.2.0",