loss,logits assignment update

[niranjanakella]

There is a assignment error in the train.py script where in the loss and logits are considered to be 'str' type after the assignment and hence have to be updated.

Line: 108 and 146

loss, logits = model(texts, attention_mask=masks, labels=labels)

Here the loss variable is assigned as a 'str' type hence the following loss.backward() would fail stating that a 'str' type doesn't have a backward method.

In the updated code in the current PR the loss and logits are re-assigned.

NOTE: Related to Issue #53