[MRG] SinkhornL1L2 bug solve

[ncassereau]

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Motivation and context / Related issue

Resolves #311

How has this been tested (if it applies)

Also setting a minimum value for alpha from now on.

Checklist

• The documentation is up-to-date with the changes I made.
• I have read the CONTRIBUTING document.
• All tests passed, and additional code has been covered with new tests.

[codecov]

Codecov Report

Merging #313 (9b94074) into master (e235b08) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #313   +/-   ##
=======================================
  Coverage   93.39%   93.39%           
=======================================
  Files          21       21           
  Lines        4887     4890    +3     
=======================================
+ Hits         4564     4567    +3     
  Misses        323      323