Remove unused mut reference

src/history.rs

@@ -87,7 +87,7 @@ impl Default for HistoryBuilder {
 
 pub struct History {
     size: usize,
-    pub batches: Vec<Batch>,
+    pub(crate) batches: Vec<Batch>,
     agents: HashMap<Index, Agent>,
     time: bool,
     mu: f64,
@@ -354,7 +354,7 @@ impl History {
             if self.time && self.batches.len() > k && self.batches[k].time == t {
                 let b = &mut self.batches[k];
 
-                b.add_events(composition, results, weights, &mut self.agents);
+                b.add_events(composition, results, weights, &self.agents);
 
                 for a in b.skills.keys() {
                     let agent = self.agents.get_mut(a).unwrap();