[mbutrovich]

Which issue does this PR close?

Closes #.

Rationale for this change

#2820 tries to bump lz4_flex but the API we use is now locked behind a feature flag. This PR handles the upgrade. It also downgrades prost since the version Comet uses was yanked.

What changes are included in this PR?

• bump lz4_flex to 0.12.0
• downgrade prost to 0.14.1

How are these changes tested?

Existing tests.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.17%. Comparing base (f09f8af) to head (adfa1f6).
⚠️ Report is 734 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2847      +/-   ##
============================================
+ Coverage     56.12%   59.17%   +3.04%     
- Complexity      976     1490     +514     
============================================
  Files           119      167      +48     
  Lines         11743    15272    +3529     
  Branches       2251     2523     +272     
============================================
+ Hits           6591     9037    +2446     
- Misses         4012     4945     +933     
- Partials       1140     1290     +150     

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[comphead]

Thanks @mbutrovich