Update openTSNE version to >=0.3

[pavlin-policar]

Issue

Due to some breaking API changes in my t-SNE implementation, I had fixed the version to 0.2.13. There are likely not going to be any more API changes, so this shouldn't be an issue anymore.

Description of changes

fastTSNE has been renamed to openTSNE in the meantime. Also, I've fixed a bug here and there from v0.2.13. I had also changed the way openTSNE.initialization.random was called, so I changed this here.

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #3552 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3552      +/-   ##
==========================================
- Coverage   83.96%   83.95%   -0.01%     
==========================================
  Files         370      370              
  Lines       66876    66876              
==========================================
- Hits        56152    56148       -4     
- Misses      10724    10728       +4

[lanzagar]

Just a reminder, that the requirement needs to be changed in the following repositories too:
https://github.com/conda-forge/orange3-feedstock
https://github.com/ales-erjavec/orange3-installers

(not a blocker for merging here)