Remove decimal_mode feature

Cargo.toml

@@ -43,6 +43,3 @@ name = "mos6502"
 bitflags = "2.5.0"
 log = "0.4.21"
 
-[features]
-decimal_mode = []
-default = ["decimal_mode"]

src/cpu.rs

@@ -1369,7 +1369,6 @@ mod tests {
         assert_eq!(cpu.registers.accumulator, 0);
     }
 
-    #[cfg(feature = "decimal_mode")]
     #[test]
     fn decimal_add_test() {
         let mut cpu = CPU::new(Ram::new(), Nmos6502);
@@ -1400,7 +1399,6 @@ mod tests {
         assert!(cpu.registers.status.contains(Status::PS_OVERFLOW));
     }
 
-    #[cfg(feature = "decimal_mode")]
     #[test]
     fn decimal_subtract_test() {
         let mut cpu = CPU::new(Ram::new(), Nmos6502);
@@ -2269,7 +2267,6 @@ mod tests {
         );
     }
 
-    #[cfg(feature = "decimal_mode")]
     #[test]
     fn adc_function_nmos6502_decimal_basic() {
         use crate::instruction::Nmos6502;