Fix docs typos in callbacks.py (#12750)

* Update callbacks.py

Signed-off-by: imyhxy <imyhxy@gmail.com>

* Update general.py

Signed-off-by: imyhxy <imyhxy@gmail.com>

---------

Signed-off-by: imyhxy <imyhxy@gmail.com>

utils/general.py

@@ -34,7 +34,7 @@ import torch
 import torchvision
 import yaml
 
-# Import 'ultralytics' package or install if if missing
+# Import 'ultralytics' package or install if missing
 try:
     import ultralytics