Fixed some new usage of format! incompatible with older versions of rustc introduced in some commit in crates/ide/src/inlay_hints.rs file

Author: KOLANICH

crates/ide/src/inlay_hints.rs

@@ -379,7 +379,7 @@ fn fn_lifetime_fn_hints(
     let mut gen_idx_name = {
         let mut gen = (0u8..).map(|idx| match idx {
             idx if idx < 10 => SmolStr::from_iter(['\'', (idx + 48) as char]),
-            idx => format!("'{idx}").into(),
+            idx => format!("'{}", idx).into(),
         });
         move || gen.next().unwrap_or_default()
     };