Update scipy requirement from <=1.15.3 to <=1.16.1

Updates the requirements on [scipy](https://github.com/scipy/scipy) to permit the latest version.
- [Release notes](https://github.com/scipy/scipy/releases)
- [Commits](scipy/scipy@v0.1.0...v1.16.1)

---
updated-dependencies:
- dependency-name: scipy
  dependency-version: 1.16.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

pyproject.toml

@@ -35,7 +35,7 @@ dependencies = [
     "pandas[excel,parquet,plot]>=2.2.0",  # brings many deps see DEPS NOTE
     "patsy>=1.0.1",  # TODO consider using formulae instead  v0.5.6
     "scikit-learn>=1.6.0",
-    "scipy<=1.15.3",  # upper pin @2025-07-14 due to https://github.com/statsmodels/statsmodels/issues/9542
+    "scipy<=1.16.1",  # upper pin @2025-07-14 due to https://github.com/statsmodels/statsmodels/issues/9542
     "seaborn<0.14", # 0.14 likely to break many plots, approach with caution
     "statsmodels>=0.14.0",
     "umap-learn",