Possible breaking changes

[matmair]

Things that would be breaking that we could change

• Squash migrations for better performance #5015
• do not require any envs on docker startup, assume local subfolder /data
• rename default python env to .venv
• Raising minimum python tp 3.10 #6420 raise to py 3.10
• rename master to main - main is the new default with a lot of tooling, and I am finding it hard to remember which project uses which

see also #6417