message: Rename fail_under to fail-under in config
  fixes
diff: @@ -150,6 +150,7 @@ pub struct Config {
  /// Run with the given profile
  pub profile: Option<String>,
  /// returns a non-zero code if coverage is below the threshold
  + #[serde(rename = "fail-under")]
  pub fail_under: Option<f64>,
  /// Result of cargo_metadata ran on the crate
  #[serde(skip_deserializing, skip_serializing)]
  