gitlab-ci: reference new docker location

*  .gitlab-ci.yml: here.

.gitlab-ci.yml

@@ -7,7 +7,7 @@ build-stable:
   stage: build
   except:
     - /^upstream/
-  image: gadl/spot-debuild:stable
+  image: registry.lrde.epita.fr/spot-debuild:stable
   script:
     - ls -l
     - ./build.sh stable
@@ -20,7 +20,7 @@ build-unstable:
   stage: build
   except:
     - /^upstream/
-  image: gadl/spot-debuild
+  image: registry.lrde.epita.fr/spot-debuild
   script:
     - ls -l
     - ./build.sh unstable