add scipy-stubs as development dependency (#2445)

* add `scipy-stubs` as dev  dependency

* add changelog entry for #2445

Author: jorenham

CHANGELOG.md

@@ -6,6 +6,8 @@
 
 ### Maintenance and fixes
 
+- Add [`scipy-stubs`](https://github.com/scipy/scipy-stubs) as a development dependency ([2445](https://github.com/arviz-devs/arviz/pull/2445))
+
 ### Documentation
 
 ## v0.21.0 (2025 Mar 06)
@@ -16,7 +18,7 @@
 - Make `arviz.data.generate_dims_coords` handle `dims` and `default_dims` consistently ([2395](https://github.com/arviz-devs/arviz/pull/2395))
 - Only emit a warning for custom groups in `InferenceData` when explicitly requested ([2401](https://github.com/arviz-devs/arviz/pull/2401))
 - Splits Bayes Factor computation out from `az.plot_bf` into `az.bayes_factor` ([2402](https://github.com/arviz-devs/arviz/issues/2402))
-- Update `method="sd"` of `mcse` to not use normality assumption ([2167](https://github.com/arviz-devs/arviz/pull/2167)) 
+- Update `method="sd"` of `mcse` to not use normality assumption ([2167](https://github.com/arviz-devs/arviz/pull/2167))
 - Add exception in `az.plot_hdi` for `x` of type `str` ([2413](https://github.com/arviz-devs/arviz/pull/2413))
 
 ### Documentation

requirements-dev.txt

@@ -8,3 +8,4 @@ pytest
 pytest-cov
 black==24.3.0
 cloudpickle<1.5.0
+scipy-stubs