[Snyk] Security upgrade python from 3.7.11-slim-buster to 3.9.13-slim-buster

[snyk-bot]

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

• backend.Dockerfile

We recommend upgrading to python:3.9.13-slim-buster, as this image has only 85 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
	714	Directory Traversal SNYK-DEBIAN10-DPKG-2847944	No Known Exploit
	514	CVE-2021-4160 SNYK-DEBIAN10-OPENSSL-2388381	No Known Exploit
	614	Loop with Unreachable Exit Condition ('Infinite Loop') SNYK-DEBIAN10-OPENSSL-2426310	No Known Exploit
	714	OS Command Injection SNYK-DEBIAN10-OPENSSL-2807585	No Known Exploit
	714	OS Command Injection SNYK-DEBIAN10-OPENSSL-2933515	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

🛠 Adjust project settings

---

Learn how to fix vulnerabilities with free interactive lessons:

🦉 Learn about vulnerability in an interactive lesson of Snyk Learn.