#45 - fix wrong response code in garden controller

src/main/java/hdm/mi/growbros/controllers/GardenController.java

@@ -74,7 +74,7 @@ public class GardenController {
             @AuthenticationPrincipal User user
     ) {
         gardenService.removeFromGarden(plantId, user);
-        return ResponseEntity.ok(null);
+        return ResponseEntity.status(204).build();
     }
 
     @DeleteMapping("/remove/all")