VoteState::deserialize_into: drop previous collections before deseria…

…lizing

sdk/program/src/vote/state/mod.rs

@@ -487,6 +487,11 @@ impl VoteState {
         input: &[u8],
         vote_state: &mut VoteState,
     ) -> Result<(), InstructionError> {
+        // assign empty collections to drop() old allocations if any
+        vote_state.votes = VecDeque::new();
+        vote_state.authorized_voters = AuthorizedVoters::default();
+        vote_state.epoch_credits = Vec::new();
+
         VoteState::deserialize_into_ptr(input, vote_state as *mut VoteState)
     }