Update hashbrown dependency.

Should resolve the problem with the transient ahash dependency (v0.7.7)
failing to build on latest nightly due to explicit check for strsimd
feature which no longer exists in nightly.

Remove unnecessary mut.

Cargo.toml

@@ -15,7 +15,7 @@ exclude = [".github/**", ".gitignore", ".rustfmt.toml"]
 
 [dependencies]
 typed-generational-arena = "0.2"
-hashbrown = "0.12.3"
+hashbrown = "0.14"
 
 [dev-dependencies]
 lazy_static = "1.4.0"

src/index.rs

@@ -91,7 +91,7 @@ impl<T: Eq + Hash + Copy + Debug> Index<T> {
         for i in 0..fields.len() {
             let field_values = field_accessors[i](doc);
             let fields_len = fields.len();
-            let mut field_details = fields.get_mut(i).unwrap();
+            let field_details = fields.get_mut(i).unwrap();
             for field_value in field_values {
                 // tokenize text
                 let terms = tokenizer(field_value);