Downgrade sign tool

[martincostello]

Downgrade the sign tool to the same version used when we published v8.4.1 to see if it's the source of the failure.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.39%. Comparing base (f7dc35f) to head (f4abd47).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2305   +/-   ##
=======================================
  Coverage   85.39%   85.39%           
=======================================
  Files         313      313           
  Lines        7461     7461           
  Branches     1126     1126           
=======================================
  Hits         6371     6371           
  Misses        745      745           
  Partials      345      345           

Flag	Coverage Δ
linux	85.39% <ø> (ø)
macos	85.39% <ø> (ø)
windows	85.36% <ø> (ø)

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