Debian: Switch from antelope to bobcat APT repository

Change-Id: Ife390597433fcededf15ecc09db626983e1b8cfd

Author: keuko

docker/base/Dockerfile.j2

@@ -252,7 +252,7 @@ COPY sources.list /etc/apt/sources.list.d/kolla-custom.list
 
 RUN apt update \
  && apt install -y --no-install-recommends extrepo \
- && extrepo enable openstack_antelope \
+ && extrepo enable openstack_bobcat \
  && apt purge -y extrepo \
  && apt --purge autoremove -y \
  && apt clean