Fixed broken URL for CaImAn requirements; Added a non-toml parse beca…

[tabedzki]

Problem

The URL in setup.py pointed to a requirements.txt that was available in a previous commit. The requirements are now stored in the pyproject.toml on a renamed 'main' branch.

Solution

I was originally going to use the tomllib to parse the file but since DataJoint supports 3.9 and tomllib requires Python 3.11, I opted to manually parse the file. I tested it on Python 3.8 and Python 3.13 which should cover the edge cases.

Once Python 3.10 is dropped, this should be changed to tomllib in a future issue.