fix: Remove nonexistent boost::coroutine2 library

[legleux]

High Level Overview of Change

Removes coroutine2 library that Conan doesn't know about.

Context of Change

Apparently coroutine is provided by context and if you try to use libxrpl it will error out because the coroutine2 lib is not being exposed.

There's no coroutine2 in the Boost Conan package

[pratikmankawde]

LGTM.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.8%. Comparing base (a518589) to head (72671e8).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #6561   +/-   ##
=======================================
  Coverage     79.8%   79.8%           
=======================================
  Files          878     878           
  Lines        67892   67892           
  Branches      7554    7551    -3     
=======================================
+ Hits         54200   54203    +3     
+ Misses       13692   13689    -3     

see 3 files with indirect coverage changes

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