[PATCH 1 of 3 3.27] [pkg] require python >= 3.4

[Philippe Pepiot]

# HG changeset patch
# User Philippe Pepiot <philippe.pepiot at logilab.fr>
# Date 1584448148 -3600
#      Tue Mar 17 13:29:08 2020 +0100
# Branch 3.27
# Node ID 87c3562b3bae1e0c73ae7637074a822aaaca093b
# Parent  af59ca8b23d0ab1c53ca0116987ccd4e89c34410
# Available At https://hg.logilab.org/review/cubicweb
#              hg pull https://hg.logilab.org/review/cubicweb -r 87c3562b3bae
[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.

diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -113,4 +113,5 @@ setup(
         ],
     },
     zip_safe=False,
+    python_requires=">=3.4",
 )