rules: remove "--parallel"

8 jobs for debian/0.18.12+dfsg-1 in 11 minutes and 47 seconds (queued for 1 minute and 4 seconds)
latest
Status Job ID Name Coverage
  Check
passed #29539
cme allowed to fail
dpkg-control

00:00:31

passed #29538
cme
dpkg-copyright

00:00:11

passed #29537
yamllint
yamllint

00:00:04

 
  Build
passed #29544
amd64 pbuilder
stretch-amd64

00:04:20

passed #29541
amd64 pbuilder
testing_unstable-amd64

00:04:41

passed #29543
amd64 pbuilder
unstable-amd64

00:05:09

failed #29540
amd64 pbuilder allowed to fail
unstable-binary-indep

00:01:19

passed #29542
amd64 pbuilder
unstable-i386

00:05:20