Fix test environment (#334)

As mentioned in #333, the test environment is currently broken due to
conda packaging changes for Python starting with version 3.15 which just
came out. This explicitly adds both `python` and `libpython` to the test
environment so that the text executables can be built.

Author: HunterBelanger

environment-dev.yml

@@ -6,6 +6,8 @@ dependencies:
   - cmake
   - ninja
   # Host dependencies
+  - python
+  - libpython
   - xtensor>=0.27,<0.28
   - numpy>=2.0
   - pybind11>=2.12.0,<4