Remove unneeded tags

The tags request hosts that are able to run a docker engine. This means
they require privileged execution. This is no longer the case, since we
use podman now. This patch removes the requirement for that.

.gitlab-ci.yml

@@ -10,8 +10,6 @@ build-master:
     - podman push "$CI_REGISTRY_IMAGE:18.04"
   only:
     - master
-  tags:
-    - docker
 
 build:
   stage: build
@@ -20,5 +18,3 @@ build:
     - podman push "$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG"
   except:
     - master
-  tags:
-    - docker