Depend on python3-grapefruit instead of python-grapefruit

Closes: #934125
8 jobs for master in 21 minutes and 21 seconds (queued for 4 seconds)
latest
Status Job ID Name Coverage
  Build
passed #397763
build

00:03:10

 
  Test
passed #397768
autopkgtest

00:02:45

passed #397769
blhc

00:01:16

passed #397767
allowed to fail
lintian

00:01:49

passed #397770
piuparts

00:18:07

passed #397766
reprotest

00:02:34

passed #397765
test-build-all

00:03:00

passed #397764
test-build-any

00:02:09