Add tag to jobs to enable shared runners

.gitlab-ci.yml

 shellcheck:
   image: koalaman/shellcheck-alpine
   script: shellcheck deploy/base/ros_entrypoint.bash scripts/*sh
+  tags:
+    - docker
 
 # The ignored rules in hadolint checks are
 # DL3006 Always tag the version of an image explicitly
@@ -16,7 +18,11 @@ dockerfiles:
     - hadolint --ignore DL3006 --ignore DL3008 deploy/base/Dockerfile || RET=1
     - hadolint --ignore DL3006 --ignore DL3008 deploy/dev/Dockerfile || RET=1
     - exit $RET
+  tags:
+    - docker
 
 yamllint:
   image: sdesbure/yamllint
   script: yamllint $(find . -name '*.yml' -o -name '*.yaml')
+  tags:
+    - docker