Refactor docker build

[michaelkaye]

The two changes are:

• do not tag both rageshake and the -debug flavour as latest - only the main build.
• Create a python:3-slim based container to host the scripts for usage.

Tested on this fork of the repo; we can see:

• the correct version is tagged latest here: https://github.com/michaelkaye/rageshake/pkgs/container/rageshake/versions?filters[version_type]=tagged
• the new docker container holding the script is here: https://github.com/michaelkaye/rageshake/pkgs/container/rageshake/scripts/versions?filters[version_type]=tagged

• the new docker container contains the script and works at a basic level

  
  michaelk@michaelk-XPS-13-9370:~$ docker run -it ghcr.io/michaelkaye/rageshake/scripts:latest python cleanup.py -h
  usage: cleanup.py [-h] (--max-days MAX_DAYS | --days-to-check DAYS_TO_CHECK)
                [--exclude-mxids-file EXCLUDE_MXIDS_FILE] [--dry-run] --path
                PATH
                LIMIT [LIMIT ...]

Cleanup rageshake files on disk

positional arguments: LIMIT application_name retention limits in days (each formatted app-name:10)

options: -h, --help show this help message and exit --max-days MAX_DAYS Search all days until this maximum --days-to-check DAYS_TO_CHECK Explicitly supply days in the past to check for deletion, eg '1,2,3,5' --exclude-mxids-file EXCLUDE_MXIDS_FILE Supply a text file containing one mxid per line to exclude from cleanup. Blank lines and lines starting # are ignored. --dry-run Dry run (do not delete) --path PATH Root path of rageshakes (eg /home/rageshakes/bugs/)

[michaelkaye]

(adding Quentin for review as we discussed these changes earlier)