Home directory for "satosa" user does not exist in satosa:bullseye

This violates the principle of least astonishment by breaking things like `pip install --user`.

As a workaround, use the **satosa:alpine** base image or do something like the following in custom images:

```
FROM satosa
[...]
USER root
RUN mkdir -p ~satosa; chown satosa:satosa ~satosa
USER satosa
[...]
```