Update base image

When doing a `docker scan lncm/tor`, the report throws out a LOT of critical vulnerabilities that need patching. At the bottom of the report, it recommends updating to Debian:11-slim to get rid of most of them

```
Project name: docker-image|lncm/tor
Docker image: lncm/tor
Platform: linux/amd64
Base image: debian:10.10-slim

**Tested 85 dependencies for known vulnerabilities, found 61 vulnerabilities.**

Base Image Vulnerabilities Severity
debian:10.10-slim 61 10 high, 6 medium, 45 low

Recommendations for base image upgrade:

Major upgrades
Base Image Vulnerabilities Severity
debian:11-slim 37 1 high, 2 medium, 34 low
```

Locate the Dockerfile entry that uses debian:10.10-slim and inspect how the image is built. Update the base image to debian:11-slim, rebuild lncm/tor, and run docker scan to verify that the reported vulnerabilities are reduced.

Written by the indexing model from the issue text.