chore: release 4.5.1 (#741)

🤖 I have created a release \*beep\* \*boop\*
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### [4.5.1](https://www.github.com/googleapis/nodejs-speech/compare/v4.5.0...v4.5.1) (2021-05-20)


### Bug Fixes

* **deps:** require google-gax v2.12.0 ([#740](https://www.github.com/googleapis/nodejs-speech/issues/740)) ([0c9c68f](https://www.github.com/googleapis/nodejs-speech/commit/0c9c68f79eee3a9132f0cf18c44a45928da2e809))
* use require() to load JSON protos ([#746](https://www.github.com/googleapis/nodejs-speech/issues/746)) ([689af48](https://www.github.com/googleapis/nodejs-speech/commit/689af48120572779143f16f7d1b0652bdddd931e))
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This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please).

speech/package.json

@@ -15,7 +15,7 @@
     "test": "c8 mocha system-test --timeout 600000"
   },
   "dependencies": {
-    "@google-cloud/speech": "^4.5.0",
+    "@google-cloud/speech": "^4.5.1",
     "@google-cloud/storage": "^5.0.0",
     "chalk": "^4.0.0",
     "node-record-lpcm16": "^1.0.1",