support action dict output

[senwu]

Description of the proposed changes

Support action output dict.

Test plan

Updated unit test.

Checklist

• [ ] I have updated the documentation accordingly.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.
• [ ] I have updated the CHANGELOG.rst accordingly.

[codecov[bot]]

Codecov Report

Merging #82 (d01ccee) into master (ac0e3ec) will increase coverage by 0.05%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #82      +/-   ##
==========================================
+ Coverage   87.88%   87.93%   +0.05%     
==========================================
  Files          38       38              
  Lines        1741     1741              
  Branches      374      374              
==========================================
+ Hits         1530     1531       +1     
  Misses        111      111              
+ Partials      100       99       -1     

Flag	Coverage Δ
unittests	87.93% <100.00%> (+0.05%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/emmental/model.py	81.94% <100.00%> (+0.34%)	:arrow_up: