Changed order of arguments to spherical_harm

[zerothi]

Since scipy 1.15 the sph_harm has been deprecated
in favor of sph_harm_y (with changed argument order).

Now sisl obeys the same order of arguments.

• Closes Incompatibility issues with scipy=1.17.0 #968
• Added tests for new/changed functions?
• Documentation for functionality in docs/
• Changes documented in changes/<num>.<type>.rst

[codecov]

Codecov Report

❌ Patch coverage is 68.75000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.67%. Comparing base (a6777eb) to head (6510145).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/sisl/utils/mathematics.py	63.63%	4 Missing ⚠️
src/sisl/_core/orbital.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #969      +/-   ##
==========================================
- Coverage   86.68%   86.67%   -0.01%     
==========================================
  Files         412      412              
  Lines       54365    54373       +8     
==========================================
+ Hits        47124    47129       +5     
- Misses       7241     7244       +3     

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