May a man attend a workshop entitled “Young women in [domain]”?
Yes, you should attend if you want to.

From their site, the point of the workshops is giving women a "platform...to present their research".

In other words, the point is that the speakers are women, not that everyone present is female.  I would expect there to be plenty of men in the audience (And if the point is to empower women, surely they are more empowered when they can share their work with everyone, not just other women).