chore(deps): update dependency google-api-core to v1.28.0 (#903)
chore(deps): update dependency google-api-core to v1.28.0 (#903)

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This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [google-api-core](https://togithub.com/googleapis/python-api-core) | `==1.27.0` -> `==1.28.0` | [![age](https://badges.renovateapi.com/packages/pypi/google-api-core/1.28.0/age-slim)](https://docs.renovatebot.com/merge-confidence/) | [![adoption](https://badges.renovateapi.com/packages/pypi/google-api-core/1.28.0/adoption-slim)](https://docs.renovatebot.com/merge-confidence/) | [![passing](https://badges.renovateapi.com/packages/pypi/google-api-core/1.28.0/compatibility-slim/1.27.0)](https://docs.renovatebot.com/merge-confidence/) | [![confidence](https://badges.renovateapi.com/packages/pypi/google-api-core/1.28.0/confidence-slim/1.27.0)](https://docs.renovatebot.com/merge-confidence/) |

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### Release Notes

<details>
<summary>googleapis/python-api-core</summary>

### [`v1.28.0`](https://togithub.com/googleapis/python-api-core/blob/master/CHANGELOG.md#&#8203;1280-httpswwwgithubcomgoogleapispython-api-corecomparev1270v1280-2021-05-20)

[Compare Source](https://togithub.com/googleapis/python-api-core/compare/v1.27.0...v1.28.0)

##### Bug Fixes

-   require google-auth>=1.25.0 ([#&#8203;190](https://www.github.com/googleapis/python-api-core/issues/190)) ([155da5e](https://www.github.com/googleapis/python-api-core/commit/155da5e18cc2fdcfa57de6f956b7d078e79cd4b7))

##### Miscellaneous Chores

-   release 1.28.0 ([#&#8203;192](https://www.github.com/googleapis/python-api-core/issues/192)) ([11b5da4](https://www.github.com/googleapis/python-api-core/commit/11b5da426a842541ca2b861d3387fc312b3f5b60))

</details>

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