chore(docker): Upgrade pnpm to version 9.15.4

[fviernau]

See https://github.com/pnpm/pnpm/releases/tag/v9.15.4.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.07%. Comparing base (cb49aeb) to head (33903c7).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #9799   +/-   ##
=========================================
  Coverage     68.07%   68.07%           
  Complexity     1284     1284           
=========================================
  Files           249      249           
  Lines          8827     8827           
  Branches        918      918           
=========================================
  Hits           6009     6009           
  Misses         2432     2432           
  Partials        386      386           

Flag	Coverage Δ
funTest-docker	65.00% <ø> (ø)
funTest-non-docker	33.36% <ø> (ø)
test-ubuntu-24.04	35.89% <ø> (ø)
test-windows-2022	35.87% <ø> (ø)

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