ci: enable Poetry cache

[browniebroke]

Committed via https://github.com/asottile/all-repos

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.43%. Comparing base (8e915a3) to head (b60be29).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #764   +/-   ##
=======================================
  Coverage   85.43%   85.43%           
=======================================
  Files           3        3           
  Lines         103      103           
  Branches       15       15           
=======================================
  Hits           88       88           
  Misses          8        8           
  Partials        7        7           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.