netplan generate: `gateway4` has been deprecated, use default routes instead

When using netplan generate I kept on getting an error message: > gateway4 has been deprecated, use default routes instead. For static IP address assignments in netplan, I've always used the structure:

network:
  version: 2
  renderer: networkd
  ethernets:
    eno1:
      dhcp4: false
      dhcp6: false
      addresses:
      - 192.168.10.10/24
      gateway4: 192.168.10.1
      nameservers:
      addresses: [192.168.10.1]

Obviously gateway4 is referencing gateway4: 192.168.10.1, but how do we fix it?