testing/polybar: switch to python3 by using newer xpp

7 jobs for !677 with polybar in 5 minutes and 29 seconds (queued for 1 second)
detached
Status Job ID Name Coverage
  Lint
passed #7128
docker-alpine x86_64
lint

00:00:17

 
  Build
passed #7133
docker-alpine ci-build aarch64
build-aarch64

00:01:30

passed #7134
docker-alpine ci-build armv7
build-armv7

00:01:33

passed #7132
docker-alpine ci-build ppc64le
build-ppc64le

00:01:21

passed #7131
docker-alpine ci-build s390x
build-s390x

00:01:18

passed #7130
docker-alpine ci-build x86
build-x86

00:02:06

passed #7129
docker-alpine ci-build x86_64
build-x86_64

00:01:09