[Snyk] Security upgrade python from 3.9.13-alpine to 3.12.0a1-alpine

[cisagovbot]

This PR was automatically created by Snyk using the credentials of a real user.

Keeping your Docker base image up-to-date means you’ll benefit from security fixes in the latest version of your chosen image. #### Changes included in this PR - Dockerfile We recommend upgrading to `python:3.12.0a1-alpine`, as this image has only 0 known vulnerabilities. To do this, merge this pull request, then verify your application still works as expected. Some of the most important vulnerabilities in your base image include: | Severity | Priority Score / 1000 | Issue | Exploit Maturity | | :------: | :-------------------- | :---- | :--------------- | |  | **500** | Use After Free
[SNYK-ALPINE316-EXPAT-3028183](https://snyk.io/vuln/SNYK-ALPINE316-EXPAT-3028183) | No Known Exploit | --- **Note:** _You are seeing this because you or someone else with access to this repository has authorized Snyk to open fix PRs._ For more information: 🧐 [View latest project report](https://app.snyk.io/org/cisagov/project/61f16888-cee9-4a8f-b168-a2905bbeba2f?utm_source=github&utm_medium=referral&page=fix-pr) 🛠 [Adjust project settings](https://app.snyk.io/org/cisagov/project/61f16888-cee9-4a8f-b168-a2905bbeba2f?utm_source=github&utm_medium=referral&page=fix-pr/settings) [//]: # 'snyk:metadata:{"prId":"913cb92e-729a-4580-bae7-10d5d0812181","prPublicId":"913cb92e-729a-4580-bae7-10d5d0812181","dependencies":[{"name":"python","from":"3.9.13-alpine","to":"3.12.0a1-alpine"}],"packageManager":"dockerfile","projectPublicId":"61f16888-cee9-4a8f-b168-a2905bbeba2f","projectUrl":"https://app.snyk.io/org/cisagov/project/61f16888-cee9-4a8f-b168-a2905bbeba2f?utm_source=github&utm_medium=referral&page=fix-pr","type":"auto","patch":[],"vulns":["SNYK-ALPINE316-EXPAT-3028183"],"upgrade":["SNYK-ALPINE316-EXPAT-3028183"],"isBreakingChange":false,"env":"prod","prType":"fix","templateVariants":["updated-fix-title","priorityScore"],"priorityScoreList":[500]}' --- **Learn how to fix vulnerabilities with free interactive lessons:** 🦉 [Learn about vulnerability in an interactive lesson of Snyk Learn.](https://learn.snyk.io/?loc=fix-pr)

[mcdonnnj]

We only use stable releases of Python.