chore: release 1.2.0 (#256)

* updated CHANGELOG.md [ci skip]

* updated package.json [ci skip]

* updated samples/package.json [ci skip]

Author: yoshi-automation

cloud-tasks/package.json

@@ -13,7 +13,7 @@
     "lint": "eslint '**/*.js'"
   },
   "dependencies": {
-    "@google-cloud/tasks": "^1.1.2",
+    "@google-cloud/tasks": "^1.2.0",
     "body-parser": "^1.18.3",
     "express": "^4.16.3",
     "yargs": "^13.0.0"