Update dataloaders.py remove float64 shapes (#8865)

May help https://github.com/ultralytics/yolov5/issues/8862

utils/dataloaders.py

@@ -478,7 +478,7 @@ class LoadImagesAndLabels(Dataset):
         [cache.pop(k) for k in ('hash', 'version', 'msgs')]  # remove items
         labels, shapes, self.segments = zip(*cache.values())
         self.labels = list(labels)
-        self.shapes = np.array(shapes, dtype=np.float64)
+        self.shapes = np.array(shapes)
         self.im_files = list(cache.keys())  # update
         self.label_files = img2label_paths(cache.keys())  # update
         n = len(shapes)  # number of images