Add is_colab() and is_kaggle() (#41)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

ultralytics/tests/data/dataloader/yolopose.py

@@ -1,6 +1,5 @@
 import cv2
 import numpy as np
-import torch
 from omegaconf import OmegaConf
 
 from ultralytics.yolo.data import build_dataloader

ultralytics/tests/functional/test_loaders.py

@@ -1,5 +1,3 @@
-import torch
-
 from ultralytics.yolo.utils.checks import check_yaml
 from ultralytics.yolo.utils.modeling.tasks import DetectionModel