.github/workflows/release: fix release workflow 2

[croissanne]

The release event isn't present when a tag is pushed, so use ref_name to
get the tag name.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.17%. Comparing base (781c3a9) to head (5e67ae9).
Report is 3 commits behind head on main.

@@           Coverage Diff           @@
##             main    #2822   +/-   ##
=======================================
  Coverage   83.17%   83.17%           
=======================================
  Files         190      190           
  Lines       22233    22233           
  Branches     2174     2174           
=======================================
  Hits        18492    18492           
  Misses       3719     3719           
  Partials       22       22           

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