chore: release 3.0.0 (#358)

* updated CHANGELOG.md

* updated package.json

* updated samples/package.json

Author: yoshi-automation

speech/package.json

@@ -11,7 +11,7 @@
     "test": "mocha system-test --timeout 600000"
   },
   "dependencies": {
-    "@google-cloud/speech": "^2.3.1",
+    "@google-cloud/speech": "^3.0.0",
     "@google-cloud/storage": "^2.0.0",
     "chalk": "^2.4.2",
     "node-record-lpcm16": "^0.3.0",