Update version number and citation request

[mfeurer]

The Pr should be pretty self-explanatory:

• update the version number to 0.14dev
• update the citation request to the JMLR version of the paper instead of the arXiv version

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: -1.46 ⚠️

Comparison is base (a4ec4bc) 81.27% compared to head (37350b5) 79.82%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1253      +/-   ##
===========================================
- Coverage    81.27%   79.82%   -1.46%     
===========================================
  Files           38       38              
  Lines         5010     5010              
===========================================
- Hits          4072     3999      -73     
- Misses         938     1011      +73     

Impacted Files	Coverage Δ
openml/__version__.py	100.00% <100.00%> (ø)

... and 7 files with indirect coverage changes

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