Future prospects at the moment seem bleak after PhD. What steps can I take now to make best use of the next 1 year?
If you want to stay in academia, you should keep working on your research portfolio. Ideally, you should do that as part of a full-time occupation, such as being a postdoc in an university or a scientist in a research lab. 

Given that you have already studied the basics of machine learning, I believe that using machine learning in your research projects would be a good way to acquire further practice, since you will be driven by a research question and will end up getting hands-ons experience with ML techniques as you try to tackle something you care about.

That said, you should keep in mind that carving a niche is very important to succeed in academia. Hence, as you consider new topics to master, you need to think about how they would fit with what you have done up to this point and what kind of academic position would that lead to.