Use Python 3 for test web server

The parts of libtest.sh and tests/make-test-runtime.sh that deal with
Python 2 are unaffected: they are only used in the flatpak-builder
tests.

Forwarded: not-needed

Gbp-Pq: Topic debian
Gbp-Pq: Name Use-Python-3-for-test-web-server.patch

flatpak (0.11.7-1) unstable; urgency=medium

  * New upstream release

[dgit import unpatched flatpak 0.11.7-1]

Import flatpak_0.11.7.orig.tar.xz

[dgit import orig flatpak_0.11.7.orig.tar.xz]

Import flatpak_0.11.7-1.debian.tar.xz

[dgit import tarball flatpak 0.11.7-1 flatpak_0.11.7-1.debian.tar.xz]