We currently use super() in the __deepcopy__ implementation ofPath

however, on the main branch of CPython this causes infinite recursion (python/cpython#126817). Although upstream may (or may not) sort out how to fix this, we should see if there is another way we can do what we need to do and avoid any fallout from changes in CPython.

Good first issue because "make sure deepcopy works on Paths" is a narrowly limited task, but hard because it will require understanding why we currently use super() and enough of the deepcopy/pickle protocol details to fix it.

attn @anntzer