Improve project metadata

Dear Task force survey. Since this repository is public, here is a suggestion from my side to add some basic metadata to it. You can could improve this within or after the merge request.

This includes:

• HMC acknowledgement
• A license (GPL because Hifis-surveyval is GPL)
• codemeta.json (json-LD standard for software metadata)
• some basic metadata in the pyproject.toml (which is the python standard).

Further you might consider:

• adding keywords, tags and other information which gitlab allows,
• a Citation.cff file
• Adding the HMC logo to the README (as we usually do for our projects)
• maybe making this a real python package, tag and release it once at least in the repo with the version the publication data was created, so that one can refer to that verison ... this is only important if in the future there will be an additional survey evaluated with a newer version of this repo, or if you would plan to do a software publication from this.

Best regards, Jens