assembler: fix clippy warnings

assembler/src/source/token_info.rs

@@ -22,6 +22,7 @@ pub struct RegisterToken {
 
 impl RegisterToken {
     /// Returns the name of a valid [`Register`]
+    #[must_use]
     pub fn name(&self) -> String {
         self.reg.to_string()
     }

assembler/src/source/tokeniser.rs

@@ -20,7 +20,7 @@ use crate::{
         source_info::SourceInfo,
         token::{Token, TokenType},
         token_info::{
-            DirectiveToken, InstructionToken, LabelToken, RegisterToken, SymbolToken,
+            DirectiveToken, LabelToken, RegisterToken, SymbolToken,
         },
     },
 };