Remove numpy<2.4 pin now that pytensor fix is released

[drbenvincent]

Summary

• remove the temporary numpy<2.4 upper bound and require pytensor>=2.38.1, now that the upstream NumPy 2.4 compatibility fix is available
• keep environment.yml aligned with pyproject.toml for these dependency requirements
• fix downstream runtime breakages triggered by NumPy 2.4 stricter scalar conversion in reporting and plotting code paths
• make scalar extraction more robust by converting scalar-like xarray outputs at API boundaries (instead of relying on fragile array-to-float coercion)
• add regression coverage for singleton-dimension xarray cases to prevent reintroducing these failures

Why this change

• the dependency pin can now be removed safely because PyTensor has shipped the needed compatibility fix
• once the pin is removed, CI and notebook execution exposed shape-related scalar conversion failures (TypeError: only 0-dimensional arrays can be converted to Python scalars)
• this PR addresses both parts together: dependency unpinning and hardening call sites so behavior remains stable on newer NumPy versions

Files changed

• pyproject.toml
• environment.yml
• causalpy/reporting.py
• causalpy/experiments/diff_in_diff.py
• causalpy/tests/test_reporting.py

Test plan

• $CONDA_EXE run -n CausalPy prek run --all-files
• $CONDA_EXE run -n CausalPy pytest causalpy/tests/test_reporting.py -q --no-cov
• $CONDA_EXE run -n CausalPy pytest causalpy/tests/test_integration_skl_examples.py::test_did causalpy/tests/test_integration_pymc_examples.py::test_did -q --no-cov

Fixes #723.

[read-the-docs-community]

Documentation build overview

📚 causalpy | 🛠️ Build #32278203 | 📁 Comparing 6ad54f3 against latest (cd89079)

  🔍 Preview build  

4 files changed

± 404.html
± _modules/causalpy/experiments/diff_in_diff.html
± _modules/causalpy/experiments/interrupted_time_series.html
± _modules/causalpy/experiments/piecewise_its.html

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.42%. Comparing base (cd89079) to head (6ad54f3).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #781      +/-   ##
==========================================
+ Coverage   94.26%   94.42%   +0.15%     
==========================================
  Files          78       78              
  Lines       12005    12061      +56     
  Branches      699      699              
==========================================
+ Hits        11317    11389      +72     
+ Misses        496      484      -12     
+ Partials      192      188       -4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[drbenvincent]

bugbot review

[cursor]

PR Summary

Medium Risk
Removes a dependency upper bound and touches core reporting/plotting numeric extraction paths; risk is mainly runtime regressions from changed array→scalar handling across xarray/numpy shapes.

Overview
Unpins NumPy (removes numpy<2.4) and bumps the minimum pytensor to >=2.38.1 in both pyproject.toml and environment.yml to support newer NumPy releases.

Hardens reporting and DiD plotting against NumPy 2.4’s stricter scalar conversion by introducing utils._as_scalar and using it across HDI/tail/ROPE/stat summary computations and annotation coordinates, plus safer np.asarray(...) conversions for OLS xarray branches.

Adds regression tests covering singleton-array/DataArray scalar extraction, singleton treated_units dims surviving reductions, HDI DataArray return paths, and OLS xarray window/counterfactual extraction conversions.

^{Written by Cursor Bugbot for commit f812477. This will update automatically on new commits. Configure here.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, have a team admin enable autofix in the Cursor dashboard.}

[drbenvincent]

All review feedback and the Bugbot suggestion have been addressed. Just needs green CI on the latest commit (6b1bec5) and Juan's re-approval to unblock merge.

I already addressed the changes