[pkg] require python >= 3.4 This avoid pip pulling a version that does not run on python2 when using a python2 environment. Since we already released some 3.27 releases in pypi, I think we should release 3.27.3 and remove releases 3.27.2, 3.27.1 and 3.27.0 from pypi.

cubicweb source: source-is-missing cubicweb/web/data/jquery.flot.js line length is * characters (>512)