Adding spsearch.py

[pedrovma]

spsearch.py: specification search strategies following Anselin, Serenini, Amaral (2024)

[codecov]

Codecov Report

Attention: Patch coverage is 3.71287% with 389 lines in your changes missing coverage. Please review.

Project coverage is 66.8%. Comparing base (9eabac4) to head (2ff9179).

Files with missing lines	Patch %	Lines
spreg/spsearch.py	3.5%	389 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #160     +/-   ##
=======================================
- Coverage   69.3%   66.8%   -2.4%     
=======================================
  Files         43      44      +1     
  Lines      10426   10830    +404     
=======================================
+ Hits        7221    7236     +15     
- Misses      3205    3594    +389     

Files with missing lines	Coverage Δ
spreg/__init__.py	100.0% <100.0%> (ø)
spreg/spsearch.py	3.5% <3.5%> (ø)