Update `Language Modeling with nn.Transformer and TorchText` tutorial

[subramen]

Fixes batchify to return tensor of shape [batch_size, seq_len] (instead of [seq_len, batch_size]).

Closes #1841

[netlify[bot]]

✅ Deploy Preview for pytorch-tutorials-preview ready!

Name	Link
🔨 Latest commit	cf4dc17fdbe46d4e9fefaf00227533a9ce263993
🔍 Latest deploy log	https://app.netlify.com/sites/pytorch-tutorials-preview/deploys/6435cc041040300008f6d52b
😎 Deploy Preview	https://deploy-preview-2074--pytorch-tutorials-preview.netlify.app/beginner/transformer_tutorial
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site settings.

[svekars]

This PR just constantly fails with:

Dec 09 22:10:55 torch.cuda.OutOfMemoryError: CUDA out of memory. Tried to allocate 1.45 GiB (GPU 0; 7.43 GiB total capacity; 6.24 GiB already allocated; 537.62 MiB free; 6.25 GiB reserved in total by PyTorch) If reserved memory is >> allocated memory try setting max_split_size_mb to avoid fragmentation.  See documentation for Memory Management and PYTORCH_CUDA_ALLOC_CONF

@malfet any thoughts?

[github-actions[bot]]

Looks like this PR hasn't been updated in a while so we're going to go ahead and mark this as Stale.
Feel free to remove the Stale label if you feel this was a mistake.
If you are unable to remove the Stale label please contact a maintainer in order to do so.
If you want the bot to never mark this PR stale again, add the no-stale label.
Stale pull requests will automatically be closed after 30 days of inactivity.