Implement step-size adaptation

[rlouf]

In this PR we implement the following step-size adaptation algorithms:

• Use DA optimization that adapts the step_size such to reach a target acceptance rate.
• A simple heuristic algorithm to find a first reasonable value.

This PR closes #40 as well.

[codecov]

Codecov Report

Merging #41 (acdd2dc) into main (f413056) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main       #41   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           10        12    +2     
  Lines          396       442   +46     
  Branches        19        23    +4     
=========================================
+ Hits           396       442   +46     

Impacted Files	Coverage Δ
aehmc/nuts.py	100.00% <ø> (ø)
aehmc/algorithms.py	100.00% <100.00%> (ø)
aehmc/hmc.py	100.00% <100.00%> (ø)
aehmc/step_size.py	100.00% <100.00%> (ø)
aehmc/trajectory.py	100.00% <100.00%> (ø)
aehmc/window_adaptation.py	100.00% <100.00%> (ø)

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[brandonwillard]

Looks good, but we definitely need to fix those Aesara errors that are showing up in the notebook.

[rlouf]

I agree. #42 was supposed to keep track of the error, but I need to fix it so the tests fail.

PS: Nothing changed in the PR, I just rebased the branch on main.