how to repel the neighbor's cats from my garden?
thank you!!

Shoot them with a water gun or a jet hand sprayer on the water hose. I use dish soap bottle filled with water and a jet sprayer like in the photo to keep my cats away from my indoor plants.

Here in Michigan in my town, you can not allow your cats to wander. A homeowner visited by unwanted cats can trap them in live traps. You then call Animal Control where they pick them up and have them fixed. If they have collars and or a micro chip, the owners are contacted. If the owners want them back there are $$$ fines involved. Otherwise they are put up for adoption.
I suggest you check with your local authorities.

Can you get your hands on pine cones? If you can, scatter them throughout your garden. You could try talking to your neighbor. I will never understand why people get cats and then let them run amuck , killing numerous birds, pooping & peeing every where, makes me nuts. Good Luck