Types of changes

alpha_min parameter for ot.optim.line_search_armijo now has default value 0. Additional boundary condition check is introduce inside of line search callback.

Motivation and context / Related issue

PR closes #502, you can find detailed analysis of the problem there.

How has this been tested (if it applies)

Existing test_sinkhorn_l1l2_transport_class test case now has explicit check for "no warnings".

PR checklist

• I have read the CONTRIBUTING document.
• The documentation is up-to-date with the changes I made (check build artifacts).
• All tests passed, and additional code has been covered with new tests.
• I have added the PR and Issue fix to the RELEASES.md file.