get CTA-KM3NeT analysis to run

• discuss with Antonio and Sara how to coordinate the migration to gammapy version 2.0 (spoken: "TWO POINT O", @shallmann will write an email to see where we stand (IMHO I would first try to agree with the people doing the work what we want to do; we can present what is being done at a later comp/soft or astro meeting thereafter. I am aware that management might have different plans on how to approach this)
• @spadmamohan depending on the reply from Sara, starting from gammapy v0.x or v1.x it would be good to get familiar with the exising analysis chain and see how fast things fail.