add Send trait bound to AnyResolver's inner

src/indexers/any.rs

@@ -44,7 +44,7 @@ pub trait RgbResolver {
 #[derive(From)]
 #[non_exhaustive]
 pub struct AnyResolver {
-    inner: Box<dyn RgbResolver>,
+    inner: Box<dyn RgbResolver + Send>,
     terminal_txes: HashMap<Txid, Tx>,
 }