Add drone config

.drone.yml

@@ -0,0 +1,24 @@
+---
+
+kind: pipeline
+type: docker
+name: default
+
+steps:
+  - name: build
+    image: plugins/docker
+    settings:
+      dry_run: yes
+
+  - name: publish
+    image: plugins/docker
+    settings:
+      auto_tag: yes
+      password:
+        from_secret: access_token
+      registry: git.luj0ga.de
+      repo: luca/matrix-prometheus
+      username: luca
+    when:
+      event:
+        - tag