Patch hint schemes

[munrojm]

Patch hint schemes to default to returning an empty dictionary for the store argument.

[codecov-commenter]

Codecov Report

Merging #447 (4a32f10) into main (2fb5a95) will decrease coverage by 0.08%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #447      +/-   ##
==========================================
- Coverage   93.58%   93.49%   -0.09%     
==========================================
  Files          67       67              
  Lines        2167     2169       +2     
==========================================
  Hits         2028     2028              
- Misses        139      141       +2     

Impacted Files	Coverage Δ
src/mp_api/routes/materials/hint_scheme.py	83.33% <0.00%> (-16.67%)	⬇️
src/mp_api/routes/summary/hint_scheme.py	87.50% <0.00%> (-12.50%)	⬇️

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