Update test cases to cover main.py file

[mingdavidqi]

ASAIK, pytest normally avoids main.py files because the name main.py doesn't match the test_*.py or *_test.py patterns wich pytest is looking for.

No idea why it's covered (42.86%) before and why it's gone now.

Tried to write some test cases to cover main.py file and updated codecov-action @ v2 beacause of https://github.com/marketplace/actions/codecov

Fixes #1885

[thehomebrewnerd]

@mingdavidqi I just realized something. I think you might just need to add an __init__.py file to the cli_tests folder. I think we ran into a similar issue a while back with Woodwork. I don't recall the details now, but I think there was some issue with tests not being used for coverage if they were in a folder without an __init__.py file.

Not completely sure this is it, but maybe something to look into.

[codecov]

Codecov Report

Merging #1927 (2fbf301) into main (3ab6880) will increase coverage by 0.21%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1927      +/-   ##
==========================================
+ Coverage   98.78%   98.99%   +0.21%     
==========================================
  Files         149      150       +1     
  Lines       16438    16456      +18     
==========================================
+ Hits        16238    16291      +53     
+ Misses        200      165      -35     

Impacted Files	Coverage Δ
featuretools/tests/cli_tests/test_cli.py	100.00% <100.00%> (ø)
featuretools/utils/cli_utils.py	91.66% <0.00%> (+37.49%)	⬆️
featuretools/__main__.py	60.71% <0.00%> (+60.71%)	⬆️

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[thehomebrewnerd]

LGTM!