message: Parse priority more foregivingly and spec complient
  4. Priority Parameters (httpbis-priority): "Unknown parameters, parameters
  with out-of-range values or values of unexpected types MUST be ignored."
diff: @@ -46,16 +46,14 @@ impl Priority {
  bare_item: BareItem::Integer(u),
  ..
  })) if (0i64..=7).contains(u) => *u as u8,
  - None => 3,
  - _ => return Err(Error::HttpFrame),
  + _ => 3,
  };
  let incremental = match dict.get("i") {
  Some(ListEntry::Item(Item {
  bare_item: BareItem::Boolean(i),
  ..
  })) => *i,
  - None => false,
  - _ => return Err(Error::HttpFrame),
  + _ => false,
  };
  Ok(Priority {
  urgency,
  