ci: Use a tag from the parallel-deqp-runner repo.

If the repo continues development, we don't want to accidentally pick
up potentially breaking changes on our next container rebuild.

Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>

.gitlab-ci/build-cts-runner.sh

@@ -2,7 +2,7 @@
 
 set -ex
 
-git clone https://gitlab.freedesktop.org/mesa/parallel-deqp-runner.git --depth 1
+git clone https://gitlab.freedesktop.org/mesa/parallel-deqp-runner.git --depth 1 -b mesa-ci-2019-11-22
 cd parallel-deqp-runner
 meson build/
 ninja -C build -j4 install