chore(deps): update dependency google-cloud-storage to v1.31.2 (#50)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [google-cloud-storage](https://togithub.com/googleapis/python-storage) | patch | `==1.31.0` -> `==1.31.2` |

---

### Release Notes

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

### [`v1.31.2`](https://togithub.com/googleapis/python-storage/blob/master/CHANGELOG.md#&#8203;1312-httpswwwgithubcomgoogleapispython-storagecomparev1311v1312-2020-09-23)

[Compare Source](https://togithub.com/googleapis/python-storage/compare/v1.31.1...v1.31.2)

### [`v1.31.1`](https://togithub.com/googleapis/python-storage/blob/master/CHANGELOG.md#&#8203;1311-httpswwwgithubcomgoogleapispython-storagecomparev1310v1311-2020-09-16)

[Compare Source](https://togithub.com/googleapis/python-storage/compare/v1.31.0...v1.31.1)

</details>

---

### Renovate configuration

:date: **Schedule**: At any time (no schedule defined).

:vertical_traffic_light: **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

:recycle: **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

:no_bell: **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [WhiteSource Renovate](https://renovate.whitesourcesoftware.com). View repository job log [here](https://app.renovatebot.com/dashboard#github/googleapis/python-vision).

Author: renovate-bot

vision/snippets/detect/requirements.txt

@@ -1,2 +1,2 @@
 google-cloud-vision==2.0.0
-google-cloud-storage==1.31.0
+google-cloud-storage==1.31.2

vision/snippets/product_search/requirements.txt

@@ -1,2 +1,2 @@
 google-cloud-vision==2.0.0
-google-cloud-storage==1.31.0
+google-cloud-storage==1.31.2