Remove unused lifetimes from app structs

src/app/states/skirmish_states/marked_cells.rs

@@ -2,18 +2,18 @@ use crate::app::states::skirmish_states::units::Units;
 use std::collections::VecDeque;
 
 #[derive(Debug, Clone, PartialEq)]
-pub struct MarkedCells<'a> {
+pub struct MarkedCells {
     pub marking_cells: bool,
     pub marked_cells: VecDeque<(usize, usize)>,
-    pub selected_unit: &'a Option<Units>,
+    pub selected_unit: Option<Units>,
 }
 
-impl MarkedCells<'_> {
+impl MarkedCells {
     pub fn new() -> Self {
         Self {
             marking_cells: false,
             marked_cells: VecDeque::new(),
-            selected_unit: &None,
+            selected_unit: None,
         }
     }
 }