Resolve clippy warnings on otg-core

otg/core/src/goban.rs

@@ -19,7 +19,7 @@ You should have received a copy of the GNU General Public License along with On
 // documenting) my code from almost a year ago.
 //
 use crate::{BoardError, Color, Size};
-use sgf::{GameNode, Move, MoveNode};
+use sgf::{GameNode, MoveNode};
 use std::collections::HashSet;
 
 #[derive(Clone, Debug, Default)]
@@ -221,7 +221,7 @@ impl Goban {
     ) -> Result<Goban, BoardError> {
         let mut s = self;
         for m in moves.into_iter() {
-            let s = match m {
+            match m {
                 GameNode::MoveNode(node) => s = s.apply_move_node(node)?,
                 GameNode::SetupNode(_n) => unimplemented!("setup nodes aren't processed yet"),
             };