Deprecating check_spat_diag

[pedrovma]

Check is done in check_weights.

This is to fix issue #146.

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 67.6%. Comparing base (c9565aa) to head (9c42c02).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
spreg/ols_regimes.py	33.3%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #147     +/-   ##
=======================================
- Coverage   67.6%   67.6%   -0.0%     
=======================================
  Files         41      41             
  Lines       9626    9622      -4     
  Branches    1433    1433             
=======================================
- Hits        6508    6504      -4     
  Misses      2704    2704             
  Partials     414     414             

Files with missing lines	Coverage Δ
spreg/ols.py	76.0% <100.0%> (+0.3%)	⬆️
spreg/twosls.py	82.5% <100.0%> (-0.1%)	⬇️
spreg/twosls_regimes.py	64.3% <100.0%> (-0.2%)	⬇️
spreg/twosls_sp_regimes.py	63.2% <ø> (-0.1%)	⬇️
spreg/user_output.py	58.0% <100.0%> (+0.3%)	⬆️
spreg/ols_regimes.py	31.8% <33.3%> (-0.7%)	⬇️