chore(deps): update dependency google-auth to v1.24.0 (#65)

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This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [google-auth](https://togithub.com/googleapis/google-auth-library-python) | minor | `==1.23.0` -> `==1.24.0` |

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### Release Notes

<details>
<summary>googleapis/google-auth-library-python</summary>

### [`v1.24.0`](https://togithub.com/googleapis/google-auth-library-python/blob/master/CHANGELOG.md#&#8203;1240-httpswwwgithubcomgoogleapisgoogle-auth-library-pythoncomparev1230v1240-2020-12-11)

[Compare Source](https://togithub.com/googleapis/google-auth-library-python/compare/v1.23.0...v1.24.0)

##### Features

-   add Python 3.9 support, drop Python 3.5 support ([#&#8203;655](https://www.github.com/googleapis/google-auth-library-python/issues/655)) ([6de753d](https://www.github.com/googleapis/google-auth-library-python/commit/6de753d585254c813b3e6cbde27bf5466261ba10)), closes [#&#8203;654](https://www.github.com/googleapis/google-auth-library-python/issues/654)

##### Bug Fixes

-   avoid losing the original '\_include_email' parameter in impersonated credentials ([#&#8203;626](https://www.github.com/googleapis/google-auth-library-python/issues/626)) ([fd9b5b1](https://www.github.com/googleapis/google-auth-library-python/commit/fd9b5b10c80950784bd37ee56e32c505acb5078d))

##### Documentation

-   fix typo in import ([#&#8203;651](https://www.github.com/googleapis/google-auth-library-python/issues/651)) ([3319ea8](https://www.github.com/googleapis/google-auth-library-python/commit/3319ea8ae876c73a94f51237b3bbb3f5df2aef89)), closes [#&#8203;650](https://www.github.com/googleapis/google-auth-library-python/issues/650)

</details>

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language/snippets/api/requirements.txt

@@ -1,3 +1,3 @@
 google-api-python-client==1.12.8
-google-auth==1.23.0
+google-auth==1.24.0
 google-auth-httplib2==0.0.4