Remove ! from todo!() in comments (#8643)

This practice makes it difficult to locate todo!s in my code when I'm
working. Let's take out the bang if we want to keep doing this.

Release Notes:

- N/A

crates/time_format/src/time_format.rs

@@ -25,8 +25,8 @@ pub fn format_localized_timestamp(
     }
     #[cfg(not(target_os = "macos"))]
     {
-        //todo!(linux) respect user's date/time preferences
-        //todo!(windows) respect user's date/time preferences
+        // todo(linux) respect user's date/time preferences
+        // todo(windows) respect user's date/time preferences
         format_timestamp_fallback(reference, timestamp, timezone)
     }
 }