gitlab-ci: Add git to build environment

.gitlab-ci.yml

@@ -12,7 +12,7 @@ test-and-build:
    - grid5000-docker
   image: debian:buster
   script:
-   - apt-get update && apt-get -y --no-install-recommends install devscripts build-essential equivs
+   - apt-get update && apt-get -y --no-install-recommends install devscripts build-essential equivs git
    - mk-build-deps -ir -t 'apt-get -y --no-install-recommends'
    - dpkg-buildpackage --no-sign
    - cp ../*deb . # needed to upload it as artifact