test: mount docker socket in pipeline

This is needed for testcontainers.

.drone.yml

@@ -42,6 +42,8 @@ steps:
         path: /drone/src/_build
       - name: app_deps
         path: /drone/src/deps
+      - name: docker_sock
+        path: /var/run/docker.sock
 
   - name: dependencies and compile
     image: &elixir 'hexpm/elixir:1.17.2-erlang-27.0.1-debian-bookworm-20240701-slim'
@@ -169,3 +171,6 @@ volumes:
     temp: {}
   - name: app_deps
     temp: {}
+  - name: docker_sock
+    host:
+      path: /var/run/docker.sock