Fix Wrong implementation of u_t(x|z) in Brownian Bridge

[selmanozleyen]

fixes #595 and changes the naming

[marcocuturi]

Thanks @selmanozleyen ! I think you need to fix the tests as well to comply with your new variable names

[codecov]

Codecov Report

Attention: Patch coverage is 72.72727% with 3 lines in your changes missing coverage. Please review.

Project coverage is 88.16%. Comparing base (2ffd45f) to head (23abcf1).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/ott/neural/methods/flows/dynamics.py	66.66%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #600      +/-   ##
==========================================
- Coverage   88.19%   88.16%   -0.04%     
==========================================
  Files          74       74              
  Lines        7760     7764       +4     
  Branches      544      544              
==========================================
+ Hits         6844     6845       +1     
- Misses        775      778       +3     
  Partials      141      141              

Files with missing lines	Coverage Δ
src/ott/neural/methods/flows/genot.py	85.12% <100.00%> (ø)
src/ott/neural/methods/flows/otfm.py	97.01% <100.00%> (ø)
src/ott/neural/methods/flows/dynamics.py	88.23% <66.66%> (-8.44%)	⬇️

[selmanozleyen]

Ok, I made the changes, it should be ready review @michalk8 @marcocuturi

[marcocuturi]

thanks @selmanozleyen :) the preferred way to ping for review is to use the tool up there, in the right, to assign reviewers :)

[michalk8]

LGTM, thanks!