chore: release 1.3.1 (#241)

Author: release-please[bot]

container/snippets/package.json

@@ -14,7 +14,7 @@
     "test": "mocha system-test --timeout 10000"
   },
   "dependencies": {
-    "@google-cloud/container": "^1.2.0"
+    "@google-cloud/container": "^1.3.1"
   },
   "devDependencies": {
     "chai": "^4.2.0",