Develop

[edkerk]

Main improvements in this PR:

• chore:
  • push Dependabot's updated dependencies to main.
• fix:
  • use python 3.9.7 in GitHub Actions (#287)

I hereby confirm that I have:

• [x] Tested my code with all requirements for running the model
• [x] Selected main as a target branch (top left drop-down menu)
• [ ] If needed, asked first in the Gitter chat room about this PR

[edkerk]

First review & merge #287.

[mihai-sysbio]

287 was merged.