Fixed gym issue

[jyan1999]

Fixed argument error when calling the featurization function. Performed sanity checks by checking the action and obs space after initialization Added one sanity check in overcooked_test.py file to verify the action & observation spaces after initialization

Fixes #68

Type of change

• [X] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change requires a documentation update

Checklist:

• [X] I have commented my code, particularly in hard-to-understand areas
• [X] I have made corresponding changes to the documentation
• [X] My changes generate no new warnings
• [X] I have added tests that prove my fix is effective or that my feature works

[codecov[bot]]

Codecov Report

Merging #104 (40f43bd) into master (0571eb0) will decrease coverage by 0.14%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #104      +/-   ##
==========================================
- Coverage   82.29%   82.15%   -0.15%     
==========================================
  Files          14       16       +2     
  Lines        3581     3709     +128     
==========================================
+ Hits         2947     3047     +100     
- Misses        634      662      +28     

Impacted Files	Coverage Δ
overcooked_ai_py/utils.py	61.11% <0.00%> (ø)
overcooked_ai_py/__init__.py	100.00% <0.00%> (ø)
overcooked_ai_py/mdp/overcooked_env.py	77.97% <0.00%> (+7.58%)	:arrow_up:

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