ci: fix version string for preview builds

[phm07]

This fixes the version string of snapshots to instead of this:
hcloud 1.50.0-dev+07d1b93-dev+07d1b93
Look like this:
hcloud 1.50.0-dev+07d1b93

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.38%. Comparing base (10bff66) to head (a883610).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1046   +/-   ##
=======================================
  Coverage   70.38%   70.38%           
=======================================
  Files         247      247           
  Lines       10867    10867           
=======================================
  Hits         7649     7649           
  Misses       2543     2543           
  Partials      675      675           

Flag	Coverage Δ
e2e	50.64% <ø> (-0.03%)	⬇️
unit	63.32% <ø> (ø)

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