chore(bindings/crypto-nodejs): Replacing into_iter by iter on &BTreeMap.

Calling `into_iter` on `&BTreeMap` will not consume it. It has the
same effect as calling `iter`. So let's do it.

bindings/matrix-sdk-crypto-nodejs/src/types.rs

@@ -51,7 +51,7 @@ impl Signatures {
     #[napi]
     pub fn get(&self, signer: &UserId) -> Option<HashMap<String, MaybeSignature>> {
         self.inner.get(signer.inner.as_ref()).map(|map| {
-            map.into_iter()
+            map.iter()
                 .map(|(device_key_id, maybe_signature)| {
                     (device_key_id.as_str().to_owned(), maybe_signature.clone().into())
                 })