Format bytes string (#6166)

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## Summary

Format bytes string

Closes #6064

## Test Plan

Added a fixture based on string's one

crates/ruff_python_formatter/src/expression/string.rs

@@ -31,7 +31,7 @@ pub enum StringLayout {
 
 impl<'a> FormatString<'a> {
     pub(super) fn new(constant: &'a ExprConstant) -> Self {
-        debug_assert!(constant.value.is_str());
+        debug_assert!(constant.value.is_str() || constant.value.is_bytes());
         Self {
             constant,
             layout: StringLayout::Default,
@@ -70,7 +70,7 @@ struct FormatStringContinuation<'a> {
 
 impl<'a> FormatStringContinuation<'a> {
     fn new(constant: &'a ExprConstant) -> Self {
-        debug_assert!(constant.value.is_str());
+        debug_assert!(constant.value.is_str() || constant.value.is_bytes());
         Self { constant }
     }
 }