chore(deps): update dependency google-cloud-storage to v1.30.0 (#63)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [google-cloud-storage](https://togithub.com/googleapis/python-storage) | minor | `==1.29.0` -> `==1.30.0` |

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### Release Notes

<details>
<summary>googleapis/python-storage</summary>

### [`v1.30.0`](https://togithub.com/googleapis/python-storage/blob/master/CHANGELOG.md#&#8203;1300-httpswwwgithubcomgoogleapispython-storagecomparev1290v1300-2020-07-24)

[Compare Source](https://togithub.com/googleapis/python-storage/compare/v1.29.0...v1.30.0)

##### Features

-   add timeouts to Blob methods where missing ([#&#8203;185](https://www.github.com/googleapis/python-storage/issues/185)) ([6eeb855](https://www.github.com/googleapis/python-storage/commit/6eeb855aa0e6a7835d1d4f6e72951e43af22ab57))
-   auto-populate standard headers for non-chunked downloads ([#&#8203;204](https://www.github.com/googleapis/python-storage/issues/204)) ([d8432cd](https://www.github.com/googleapis/python-storage/commit/d8432cd65a4e9b38eebd1ade2ff00f2f44bb0ef6)), closes [#&#8203;24](https://www.github.com/googleapis/python-storage/issues/24)
-   migrate to Service Account Credentials API ([#&#8203;189](https://www.github.com/googleapis/python-storage/issues/189)) ([e4990d0](https://www.github.com/googleapis/python-storage/commit/e4990d06043dbd8d1a417f3a1a67fe8746071f1c))

##### Bug Fixes

-   add multiprocessing.rst to synthool excludes ([#&#8203;186](https://www.github.com/googleapis/python-storage/issues/186)) ([4d76e38](https://www.github.com/googleapis/python-storage/commit/4d76e3882210ed2818a43256265f6df31348d410))

##### Documentation

-   fix indent in code blocks ([#&#8203;171](https://www.github.com/googleapis/python-storage/issues/171)) ([62d1543](https://www.github.com/googleapis/python-storage/commit/62d1543e18040b286b23464562aa6eb998074c54)), closes [#&#8203;170](https://www.github.com/googleapis/python-storage/issues/170)
-   remove doubled word in docstring ([#&#8203;209](https://www.github.com/googleapis/python-storage/issues/209)) ([7a4e7a5](https://www.github.com/googleapis/python-storage/commit/7a4e7a5974abedb0b7b2e110cacbfcd0a40346b6))

##### Documentation

-   fix indent in code blocks ([#&#8203;171](https://www.github.com/googleapis/python-storage/issues/171)) ([62d1543](https://www.github.com/googleapis/python-storage/commit/62d1543e18040b286b23464562aa6eb998074c54)), closes [#&#8203;170](https://www.github.com/googleapis/python-storage/issues/170)
-   remove doubled word in docstring ([#&#8203;209](https://www.github.com/googleapis/python-storage/issues/209)) ([7a4e7a5](https://www.github.com/googleapis/python-storage/commit/7a4e7a5974abedb0b7b2e110cacbfcd0a40346b6))

##### Dependencies

-   prep for grmp-1.0.0 release ([#&#8203;211](https://www.github.com/googleapis/python-storage/issues/211)) ([55bae9a](https://www.github.com/googleapis/python-storage/commit/55bae9a0e7c0db512c10c6b3b621cd2ef05c9729))

</details>

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asset/snippets/snippets/requirements.txt

@@ -1,4 +1,4 @@
-google-cloud-storage==1.29.0
+google-cloud-storage==1.30.0
 google-cloud-asset==2.0.0
 google-cloud-resource-manager==0.30.2
 google-cloud-pubsub==1.7.0