ci(docker): fix paths string

Paths are not checked recursively by default.

Signed-off-by: Randolph Sapp <[email protected]>

.github/workflows/docker.yml

@@ -4,7 +4,7 @@ on:
   push:
     branches: [master]
     paths:
-      - docker
+      - 'docker/**'
       - requirements.txt
 
 env: