Remove dependency on goprocess

[gammazero]

The dependency on goprocess is not needed by boxo, and removing it removes the need to support it in code dependent on boxo.

Closes #709

[codecov]

Codecov Report

Attention: Patch coverage is 72.99270% with 37 lines in your changes missing coverage. Please review.

Project coverage is 60.39%. Comparing base (29598b2) to head (d15e952).

Files with missing lines	Patch %	Lines
bootstrap/bootstrap.go	39.62%	31 Missing and 1 partial ⚠️
bitswap/server/server.go	92.50%	3 Missing ⚠️
bitswap/client/client.go	81.81%	2 Missing ⚠️

@@           Coverage Diff           @@
##             main     #710   +/-   ##
=======================================
  Coverage   60.39%   60.39%           
=======================================
  Files         243      243           
  Lines       31025    31040   +15     
=======================================
+ Hits        18737    18747   +10     
- Misses      10621    10627    +6     
+ Partials     1667     1666    -1     

Files with missing lines	Coverage Δ
bitswap/bitswap.go	67.05% <100.00%> (-0.39%)	⬇️
bitswap/server/internal/decision/engine.go	91.48% <100.00%> (+0.04%)	⬆️
namesys/republisher/repub.go	61.26% <100.00%> (+2.60%)	⬆️
bitswap/client/client.go	87.93% <81.81%> (-0.14%)	⬇️
bitswap/server/server.go	63.08% <92.50%> (-1.13%)	⬇️
bootstrap/bootstrap.go	30.90% <39.62%> (-1.05%)	⬇️

... and 8 files with indirect coverage changes