message: Improve error msg for get target runner
diff: @@ -409,7 +409,7 @@ fn target_runner(
  let matching_runner = cfgs.next();
  if let Some((key, runner)) = cfgs.next() {
  anyhow::bail!(
  - "several matching instances of `target.'cfg(..)'.runner` in `.cargo/config`\n\
  + "several matching instances of `target.'cfg(..)'.runner` in configurations\n\
  first match `{}` located in {}\n\
  second match `{}` located in {}",
  matching_runner.unwrap().0,
  