fix(clippy1): Updated code to test correctness clippy lint with approx_constant lint rule

closes #888

exercises/clippy/clippy1.rs

@@ -8,10 +8,16 @@
 
 // I AM NOT DONE
 
+use std::f32;
+
 fn main() {
-    let x = 1.2331f64;
-    let y = 1.2332f64;
-    if y != x {
-        println!("Success!");
-    }
+    let pi = 3.14f32;
+    let radius = 5.00f32;
+
+    let area = pi * f32::powi(radius, 2);
+
+    println!(
+        "The area of a circle with radius {:.2} is {:.5}!",
+        radius, area
+    )
 }