Fix invalid yaml

This fixes the error
```
ERROR: yaml.parser.ParserError: while parsing a block collection
  in "./docker-compose.yml", line 80, column 7
expected <block end>, but found '?'
  in "./docker-compose.yml", line 81, column 7
```

when you run

```
docker-compose pull && docker-compose up
```

docker-compose.yml

@@ -78,12 +78,12 @@ services:
     container_name: mainsail
     ports:
       - 8011:80
-      depends_on: 
-        - klipper
-        # - klipper_another_printer
+    depends_on: 
+      - klipper
+      # - klipper_another_printer
     links:
       - klipper:klipper
       # - klipper_another_printer:klipper_another_printer
 
 volumes: 
-  gcode_files:
+  gcode_files: