chore: Remove version attribute from compose file (#4869)

- Removes the warning the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion

Signed-off-by: Thomas Camlong <[email protected]>

Author: ajnart

contrib/docker/docker-compose.yml

@@ -1,4 +1,3 @@
-version: '3.8'
 services:
   dragonfly:
     image: 'docker.dragonflydb.io/dragonflydb/dragonfly'
@@ -13,4 +12,4 @@ services:
     volumes:
       - dragonflydata:/data
 volumes:
-  dragonflydata:
+  dragonflydata: