parsers: Replace std stuff with alloc/core stuff

parsers/src/message.rs

@@ -5,9 +5,9 @@
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 use crate::ns;
+use alloc::collections::BTreeMap;
 use jid::Jid;
 use minidom::Element;
-use std::collections::BTreeMap;
 use xso::error::{Error, FromElementError};
 
 /// Should be implemented on every known payload of a `<message/>`.
@@ -256,7 +256,7 @@ impl Message {
             }
         }
         buf.extend(iter);
-        std::mem::swap(&mut buf, &mut self.payloads);
+        core::mem::swap(&mut buf, &mut self.payloads);
         result
     }