Use local random state in ot.datasets.make_data_classif

[kachayev]

Types of changes

Switch from np.random.randn to rng.randn when generating make_data_classif dataset with dataset='2gauss_prop'.

Motivation and context / Related issue

It's not desirable to change global state. And it's already done for other datasets in the same function.

How has this been tested (if it applies)

n/a

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.

[codecov]

Codecov Report

Merging #510 (40ee453) into master (9dd4d8d) will not change coverage.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #510   +/-   ##
=======================================
  Coverage   96.05%   96.05%           
=======================================
  Files          65       65           
  Lines       13667    13667           
=======================================
  Hits        13128    13128           
  Misses        539      539           

[agramfort]

good catch