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/collab/src/main.rs

@@ -130,7 +130,7 @@ async fn main() -> Result<()> {
                 })
                 .await?;
 
-            // todo!("windows")
+            // todo("windows")
             #[cfg(windows)]
             unimplemented!();
         }