chore(deps): update python docker tag to v3.8.2 (#3206)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| python | final | patch | `3.8.0b1` -> `3.8.2` |

---

### 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**: Never, 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#GoogleCloudPlatform/python-docs-samples).

Author: renovate-bot

trace/cloud-trace-demo-app/app/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.8.0b1
+FROM python:3.8.2
 
 RUN pip3 install --upgrade pip