Replace poetry with uv

[smilesun]

No description provided.

[smilesun]

@Alex-Markham, I added this line since in the root directory of our repository we have directories called submodules and uv can not figure out which one is the package but in general, where should be "." instead of 1 directory futher. Do you have experience on this. I guess using "." might be the correct one so that the installed package can be imported but in our case we have submodules, so where="." is not possible.

[Alex-Markham]

the usual setup (according to most recent style guides) would be to put move the causalspyne/ dir to src/causalspyne, and then uv will find it automatically

[Alex-Markham]

on my machine now, uv run pytest results in all passing tests, but that's for Python 3.12. My suggestion is that we only support >=3.12 and we adjust the github action tests accordingly

[smilesun]

i tried on my machine with simply changing the version from 0.1.5 to 0.1.6, and upload to pypi and it works!, so i will merge this PR

[smilesun]

changes of this PR is cloned to #53