[contributor wanted] Quicker uncertainties for weighted data

[jonas-eschle]

The current uncertainty calculation using hesse with weighted likelihoods is precise, using the asymptotically correct formula (see https://link.springer.com/article/10.1140/epjc/s10052-022-10254-8), but expensive (as it creates the full Jacobian of the values).
Sometimes, i.e. for quick checks, a faster alternative method could be helpful, as described in the paper.

This needs a function which calculates the alternative and can be added as an option to hesse.

Please just write here if you're interested and we'll assist with the implementation and guidance, also beginners are welcome!