Align documented SciPy lower bound with package metadata

[shawcharles]

I noticed a small dependency-floor drift.

pyproject.toml requires scipy>=1.10, with an inline comment explaining that lower_limit= support is needed for scipy.stats.multivariate_normal.cdf(...). Four documentation/docs-build surfaces still say or install an older SciPy floor:

• README requirements: scipy >= 1.7
• Read the Docs post-install: scipy>=1.7.0
• docs Sphinx build workflow: scipy>=1.7.0
• docs dependency smoke workflow on Python 3.9: scipy>=1.7.0

Would you accept a narrow consistency PR that updates those references to scipy>=1.10 only?

Proposed scope:

• update those four active lower-bound references;
• leave normal test workflows that install latest scipy unchanged;
• avoid code changes, runtime metadata changes, new CI jobs, and dependency-policy changes.

Validation I will run:

• search guard for remaining active scipy>=1.7 lower-bound claims;
• Python 3.9 docs dependency install smoke;
• docs snippet and doc-dependency integrity tests;
• Sphinx HTML build with warnings treated as errors.