Deprecate method argument in favor of inference_method

[aloctavodia]

Following discussion in #553

[tomicapretto]

Apart from the small comment, looks good to me!

[codecov-commenter]

Codecov Report

Merging #554 (878d8c6) into main (236021f) will decrease coverage by 0.50%.
The diff coverage is 88.46%.

❗ Current head 878d8c6 differs from pull request most recent head a43ad64. Consider uploading reports for the commit a43ad64 to get more accurate results

@@            Coverage Diff             @@
##             main     #554      +/-   ##
==========================================
- Coverage   86.93%   86.42%   -0.51%     
==========================================
  Files          32       32              
  Lines        2655     2675      +20     
==========================================
+ Hits         2308     2312       +4     
- Misses        347      363      +16     

Impacted Files	Coverage Δ
bambi/models.py	85.25% <71.42%> (-4.50%)	⬇️
bambi/backend/pymc.py	82.75% <80.00%> (+1.53%)	⬆️
bambi/tests/test_built_models.py	99.03% <100.00%> (+0.03%)	⬆️

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