💚 Fix GitHub Actions Poetry setup

[tiangolo]

💚 Fix GitHub Actions Poetry setup.

Ref: https://github.blog/changelog/2020-10-01-github-actions-deprecating-set-env-and-add-path-commands/

[codecov]

Codecov Report

Merging #21 (1e0fd50) into master (2b87140) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master       #21   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          127       127           
=========================================
  Hits           127       127           

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