chore: release 2.8.1 (#497)

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>

Author: release-please[bot]

kms/package.json

@@ -14,7 +14,7 @@
     "test": "c8 mocha --recursive test/ --timeout=800000"
   },
   "dependencies": {
-    "@google-cloud/kms": "^2.8.0",
+    "@google-cloud/kms": "^2.8.1",
     "fast-crc32c": "^2.0.0",
     "jslint": "^0.12.1"
   },