deps: remove polkadot-sdk umbrella crate (#1926)

* deps: get rid of polkadot-sdk umbrella crate

* fix nits

* Update subxt/src/backend/mod.rs

* Update subxt/src/events/events_client.rs

* Update metadata/src/utils/validation.rs

* cargo clippy fix

* fix ui tests

core/src/events.rs

@@ -181,10 +181,8 @@ impl<T: Config> Events<T> {
     /// them, and return only those which should decode to the provided `Ev` type.
     /// If an error occurs, all subsequent iterations return `None`.
     pub fn find<Ev: StaticEvent>(&self) -> impl Iterator<Item = Result<Ev, Error>> + '_ {
-        self.iter().filter_map(|ev| {
-            ev.and_then(|ev| ev.as_event::<Ev>().map_err(Into::into))
-                .transpose()
-        })
+        self.iter()
+            .filter_map(|ev| ev.and_then(|ev| ev.as_event::<Ev>()).transpose())
     }
 
     /// Iterate through the events using metadata to dynamically decode and skip