Formatter (#51)

Enforce consistent formatting use `dprint`

book/src/02_basic_calculator/04_panics.md

@@ -13,7 +13,7 @@ fn speed(start: u32, end: u32, time_elapsed: u32) -> u32 {
 If you have a keen eye, you might have spotted one issue[^one]: what happens if `time_elapsed` is zero?
 
 You can try it
-out [on the Rust playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=36e5ddbe3b3f741dfa9f74c956622bac)!  
+out [on the Rust playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=36e5ddbe3b3f741dfa9f74c956622bac)!\
 The program will exit with the following error message:
 
 ```text
@@ -21,7 +21,7 @@ thread 'main' panicked at src/main.rs:3:5:
 attempt to divide by zero
 ```
 
-This is known as a **panic**.  
+This is known as a **panic**.\
 A panic is Rust's way to signal that something went so wrong that
 the program can't continue executing, it's an **unrecoverable error**[^catching]. Division by zero classifies as such an
 error.