Removes ouroboros dependency

[brooksprumo]

Problem

The ouroboros dependency is no longer used in accounts-db (or anywhere!), and we probably do not want to add new self-referential structs if possible.

Summary of Changes

Remove it.

[CriesofCarrots]

I think accounts-db was the only ouroboros user...? The crate is listed in the runtime Cargo.toml, but I don't see it imported anywhere. Maybe we can remove the dependency from the workspace?

[brooksprumo]

I think accounts-db was the only ouroboros user...? The crate is listed in the runtime Cargo.toml, but I don't see it imported anywhere. Maybe we can remove the dependency from the workspace?

Will do!

[CriesofCarrots]

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.8%. Comparing base (6ee3bb9) to head (c6656dd).
Report is 12 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #35355    +/-   ##
========================================
  Coverage    81.7%    81.8%            
========================================
  Files         834      834            
  Lines      224299   224834   +535     
========================================
+ Hits       183361   183918   +557     
+ Misses      40938    40916    -22     

[jeffwashington]

lgtm