Has it been discovered that the forces are biased against employing women and/or people from ethnic minorities? If yes then that should of course be addressed. If it's the case that less women and ethnic minorities apply to join the forces for undefined reasons then fine, encourage those groups to apply during recruitment drives etc.
However, when it comes to the forces, I'm not convinced setting targets is the correct approach.
I'll say something else that I'll no doubt get shouted down for. When you watch these fly on the wall police tv shows, you'll notice they now employ men and women that are quite short in stature. Ok, this was maybe done due to less people in general applying to join, I don't know the reasons behind reducing the height requirement.
However, there's short and then there's short. Result? When something kicks off, they often need to wait for taller more athletic officers to arrive. Then you see the ones that are overweight (sometimes obviously so) and they can't run for toffee. But hey, let's just laugh all these things off. It's more important to tick various diversity boxes than ensure we have forces that are genuinely fit for purpose.