feat(ci): Build docker container

.drone.yml

@@ -63,6 +63,11 @@ steps:
       # Run tests
       - mix test
 
+  - name: build & publish container
+    image: docker.io/library/elixir:1.18.3-otp-27
+    commands:
+      - docker build --tag mitgliederverwaltung .
+
 ---
 kind: pipeline
 type: docker