Rename Experiment.summary() argument

[al-rigazzi]

This PR addresses the shadowing of the builitin symbol format in the signature of the Experiment.summary() member function.

A lint pragma instruction could be removed, following renaming of format to style. As the argument name changes, this has to be considered and API break.

[codecov]

Codecov Report

Merging #391 (b30cc3c) into develop (b509efd) will decrease coverage by 0.12%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #391      +/-   ##
===========================================
- Coverage    89.77%   89.66%   -0.12%     
===========================================
  Files           59       59              
  Lines         3618     3618              
===========================================
- Hits          3248     3244       -4     
- Misses         370      374       +4     

Files	Coverage Δ
smartsim/experiment.py	80.95% <100.00%> (ø)

... and 1 file with indirect coverage changes

[mellis13]

Thanks, LGTM!