Added .lower() method to label
Author: Himanshunitrr
Pull request: yes

Same labels with different cases (like "Hindi", "hindi", "hIndi") can be passed and the predicted scores vary a lot. So if we add .lower() method we can solve that.

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Comments:
Thanks for the proposal. It's a good thought, but I actually am not sure this is what we want to do. While it may seem intuitively to make sense that different cases shouldn't affect the scores, I don't think we want to unilaterally send everything to lower case.

One reason is that casing actually can provide an important signal. For example, capitalizing the A in "Apple" might be useful for the model to determine whether you mean the fruit or the tech giant. I think in general, it would be best to leave this to the user to decide how they want to pass the candidate labels' casing.

Ok