Ignore pins on Dockerfile references

gitlab_deps/deps.py

@@ -85,7 +85,7 @@ def get_explicit_deps(gl, project_path, branch_name):
         return []
 
 
-_docker_image_rx = re.compile(r'^([^/]*)(/([^:]*))?(:(.*))?$')
+_docker_image_rx = re.compile(r'^([^/]*)(/([^:]*))?(:([^@]*))?(@.*)?$')
 
 
 def docker_image_to_project(docker_image, registry_hostname):