Work around uwsgi breakage

uwsgi broke installation from source with their latest release [0].
Since we want to move away from source installation anyway, make
grenade based jobs non-voting for the moment so that we can backport
[1] properly.

[0] https://bugs.launchpad.net/bugs/1883468
[1] https://review.opendev.org/577955

Related-Bug: 1883468
Change-Id: I8e47bb7c70031a4df7f1af6b811df4c6cc784b2a
1 file changed