update pyproject.toml and pixi env (#195)

redirect xattree, drop uv and just use pixi

Author: wpbonelli

.gitignore

@@ -9,6 +9,3 @@ venv/
 # pixi environments
 .pixi
 *.egg-info
-
-# uv lockfile
-uv.lock

docs/dev/sdd.md

@@ -103,7 +103,7 @@ Minimal class definitions are easier to read and to generate from definition fil
 
 The product bolts on dictionary-style behavior by implementing `MutableMapping` in a component base class.
 
-Where `imod-python` components expose their fields via [a `Dataset`](https://github.com/Deltares/imod-python/blob/master/imod/common/interfaces/ipackagebase.py), components in the product expose a `DataTree` node. The [`DataTree`](https://docs.xarray.dev/en/stable/generated/xarray.DataTree.html) is a recently developed `xarray` feature implementing [a hierarchical data store](https://docs.xarray.dev/en/stable/user-guide/hierarchical-data.html). Components in the product are an [experimental hybrid](https://github.com/modflowpy/xattree) of `attrs` and `xarray` where `attrs` properties, as well as parent/child references, are proxied through the `DataTree`.
+Where `imod-python` components expose their fields via [a `Dataset`](https://github.com/Deltares/imod-python/blob/master/imod/common/interfaces/ipackagebase.py), components in the product expose a `DataTree` node. The [`DataTree`](https://docs.xarray.dev/en/stable/generated/xarray.DataTree.html) is a recently developed `xarray` feature implementing [a hierarchical data store](https://docs.xarray.dev/en/stable/user-guide/hierarchical-data.html). Components in the product are an [experimental hybrid](https://github.com/wpbonelli/xattree) of `attrs` and `xarray` where `attrs` properties, as well as parent/child references, are proxied through the `DataTree`.
 
 Combining `attrs` and `xarray` in this way presents challenges involving duplication (`xarray` prefers copies to in-place updates) and synchronization. Some careful management of parent/child links is still required, even though `DataTree` does the majority of the work.