Missing required package "patch" in Fedora setup instructions

I'm on Fedora 34 and I didn't have the `patch` tool installed.
I'm pretty sure I didn't uninstall it if it was a default package, so I think it isn't a default package.
So I think the readme in this repo should be updated to mention that patch is a required tool on the host (I had to re-download mono entirely in order to be sure the patches were applied by the script).