Bug#916817: transition: remove python3.6

[Matthias Klose]

that's what I used for Ubuntu:

title = "Drop Python3.6 compiled extensions";
is_affected = .build-depends ~ /python3(-all)?-dev|python3|python3.6|python3.7/;
is_good = .depends ~ /python3 \(>= 3\.7\~\)/ | .depends ~ /libpython3\.7/  |
.depends ~ /python3\.7/;
is_bad = .depends ~ /python3 \(>= 3\.6\~\)/ | .depends ~ /libpython3\.6/  |
.depends ~ /python3\.6/;