[Clarification Chapter 3] FutureWarning: elementwise comparison failed; returning scalar instead

This is a warning I got while running the Binary Classifier (5 Detector) code from Chapter 3 specifically when I was creating the subset of the dataset with only 5's on the train and test set.
```
y_train_5 = (y_train == 5)
y_test_5 = (y_test == 5)
```
This error forbids me from running the SGDClassifier in the next code block of the book/jupyter notebook since y is not 1D array.

Also realized that the same error is still open as an issue on [numpy](https://github.com/numpy/numpy/issues/6784) and [pandas](https://github.com/pandas-dev/pandas/issues/7830) repositories.

I'm using the versions mentioned in the readme of this repository.

Any help regarding this is appreciated. If a similar issue exists, please leave a comment and I'll close this.

Thanks!