chore(main): release 4.0.0 (#372)

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md
Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: release-please[bot]

secret-manager/package.json

@@ -14,7 +14,7 @@
     "test": "c8 mocha --recursive test/ --timeout=800000"
   },
   "dependencies": {
-    "@google-cloud/secret-manager": "^3.12.0"
+    "@google-cloud/secret-manager": "^4.0.0"
   },
   "devDependencies": {
     "c8": "^7.0.0",