up python 26 jobs to 60 minute time outs

neutron 26 jobs are actually regularly hitting the 40 minute
timeout on unit tests, as their actual unit tests take ~32 minutes
and there is current a performance issue on subunit report
processing that makes it take ~9 minutes (on 27, 26 might be slower
still).

This means that completely passing unit test runs are reseting the
gate due to a timeout limit.

60 minutes should be sufficient to get us past this issue, and let
us figure out the subunit performance issue. However given neutron
unit test growth, 40 minutes is probably too low anyway.

Change-Id: If4bb799d9b6fe8815280aca9f28fee8a65a477c6