Update edition to 2021

- Remove TryFrom/Into and FromIterator imports
- Prevent impl_validator_using_provider macro in sasl crate from
  constructing trait object

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

minidom/src/node.rs

@@ -13,7 +13,6 @@ use crate::error::Result;
 
 use rxml::writer::Item;
 
-use std::convert::TryInto;
 use std::io::Write;
 
 /// A node in an element tree.