Upgrading Cargo.toml 
from
serde-xml-rs = "0.2.1"
to
serde-xml-rs = "0.3.1"

build.rs
from
use serde_xml_rs::deserialize;
to
extern crate serde_xml_rs;

from
let mut rcc: RCC = deserialize(&bytes[..]).unwrap_or_else(|e| panic!("could not parse {}: {}", qrc.display(), e));
to
let mut rcc: RCC = serde_xml_rs::from_reader(&bytes[..]).unwrap_or_else(|e| panic!("could not parse {}: {}", qrc.display(), e));

One way to upgrade from .2 to .3, but it may not be the best way, so I will put an upgrade on a wishlist.