chore(deps): update dependency ts-loader to v9 (#203)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [ts-loader](https://togithub.com/TypeStrong/ts-loader) | [`^8.0.0` -> `^9.0.0`](https://renovatebot.com/diffs/npm/ts-loader/8.1.0/9.0.0) | [![age](https://badges.renovateapi.com/packages/npm/ts-loader/9.0.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/npm/ts-loader/9.0.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/npm/ts-loader/9.0.0/compatibility-slim/8.1.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/npm/ts-loader/9.0.0/confidence-slim/8.1.0)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>TypeStrong/ts-loader</summary>

### [`v9.0.0`](https://togithub.com/TypeStrong/ts-loader/blob/master/CHANGELOG.md#v900)

[Compare Source](https://togithub.com/TypeStrong/ts-loader/compare/v8.1.0...v9.0.0)

Breaking changes:

-   minimum webpack version: 5
-   minimum node version: 12

Changes:

-   [webpack 5 migration](https://togithub.com/TypeStrong/ts-loader/pull/1251) - thanks [@&#8203;johnnyreilly](https://togithub.com/johnnyreilly), [@&#8203;jonwallsten](https://togithub.com/jonwallsten), [@&#8203;sokra](https://togithub.com/sokra), [@&#8203;appzuka](https://togithub.com/appzuka), [@&#8203;alexander-akait](https://togithub.com/alexander-akait)

</details>

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Author: renovate-bot

packages/google-cloud-documentai/package.json

@@ -46,7 +46,7 @@
     "null-loader": "^4.0.0",
     "pack-n-play": "^1.0.0-2",
     "sinon": "^10.0.0",
-    "ts-loader": "^8.0.0",
+    "ts-loader": "^9.0.0",
     "typescript": "^3.8.3",
     "webpack": "^5.0.0",
     "webpack-cli": "^4.0.0",