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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