fix(optimization_tutorial): replace deprecated ToTensor with v2 transforms (#3870)

Fixes #3854 

## Description
- Replace deprecated `torchvision.transforms.ToTensor()` with
`v2.Compose([v2.ToImage(), v2.ToDtype(torch.float32, scale=True)])` in
`beginner_source/basics/optimization_tutorial.py`
- Aligns the tutorial with the supported torchvision v2 transforms API
(ToTensor deprecated since torchvision 0.16)

## Checklist
- [x] The issue that is being fixed is referred in the description (see
above "Fixes #ISSUE_NUMBER")
- [x] Only one issue is addressed in this pull request
- [x] Labels from the issue that this PR is fixing are added to this
pull request
- [x] No unnecessary issues are included into this pull request.

cc @subramen @svekars

Co-authored-by: sekyondaMeta <127536312+sekyondaMeta@users.noreply.github.com>

Author: Kadermiyanyedi

beginner_source/basics/optimization_tutorial.py

@@ -28,20 +28,20 @@
 from torch import nn
 from torch.utils.data import DataLoader
 from torchvision import datasets
-from torchvision.transforms import ToTensor
+from torchvision.transforms import v2
 
 training_data = datasets.FashionMNIST(
     root="data",
     train=True,
     download=True,
-    transform=ToTensor()
+    transform=v2.Compose([v2.ToImage(), v2.ToDtype(torch.float32, scale=True)])
 )
 
 test_data = datasets.FashionMNIST(
     root="data",
     train=False,
     download=True,
-    transform=ToTensor()
+    transform=v2.Compose([v2.ToImage(), v2.ToDtype(torch.float32, scale=True)])
 )
 
 train_dataloader = DataLoader(training_data, batch_size=64)