Sure, technically CAT 5 is not rated for GigE, but that's measured over longer distances, typically 100M. CAT 5e is officially rated for GigE. There's no benefit to going to higher rated cabling.
Some might argue that they buy the higher rated cables because it is easier to get shielded versions that way. However, it's not clear that a shielded Ethernet cable has ever solved any problems where our radios are concerned (war stories to the contrary are welcome

Here's an excellent video where short CAT 5 through CAT 8 cables were tested at 10 Gbit/s, ten times faster than our radios work at. There's no perceptible difference between them. Sorry for the link, but embedding was not allowed for this video.
https://youtu.be/2ILqXuDpzd8