fix(deps): update dependency promise-mysql to v5 (#2101)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [promise-mysql](https://togithub.com/lukeb-uk/node-promise-mysql) | [`^4.0.0` -> `^5.0.0`](https://renovatebot.com/diffs/npm/promise-mysql/4.1.4/5.0.0) | [![age](https://badges.renovateapi.com/packages/npm/promise-mysql/5.0.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/npm/promise-mysql/5.0.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/npm/promise-mysql/5.0.0/compatibility-slim/4.1.4)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/npm/promise-mysql/5.0.0/confidence-slim/4.1.4)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>lukeb-uk/node-promise-mysql</summary>

### [`v5.0.0`](https://togithub.com/lukeb-uk/node-promise-mysql/compare/7c102d71775700a8c9cb17962d36366497ee831c...6cd7cc6c0371962259a9fc97c1a96b51b30f8e1b)

[Compare Source](https://togithub.com/lukeb-uk/node-promise-mysql/compare/7c102d71775700a8c9cb17962d36366497ee831c...6cd7cc6c0371962259a9fc97c1a96b51b30f8e1b)

</details>

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cloud-sql/mysql/mysql/package.json

@@ -20,7 +20,7 @@
     "@google-cloud/logging-winston": "^4.0.0",
     "body-parser": "^1.19.0",
     "express": "^4.17.1",
-    "promise-mysql": "^4.0.0",
+    "promise-mysql": "^5.0.0",
     "prompt": "^1.0.0",
     "pug": "^3.0.0",
     "winston": "^3.1.0"