Fix bug in fit_MAP when shared variables are used in graph (pymc-devs#468)

* Fix bug in `fit_MAP` when shared variables are used in graph

* Delay jax import

* Try version pinning dask

* Pin dask version in setup.py

Author: jessegrabowski

conda-envs/windows-environment-test.yml

@@ -0,0 +1,17 @@
+name: pymc-extras-test
+channels:
+- conda-forge
+- defaults
+dependencies:
+- pip
+- pytest-cov>=2.5
+- pytest>=3.0
+- dask<2025.1.1
+- xhistogram
+- statsmodels
+- numba<=0.60.0
+- pymc>=5.21
+- pip:
+  - blackjax
+  - scikit-learn
+  - better_optimize