fix clippy::approx_constant in tests

Author: hellow554

tests/test_std.rs

@@ -1091,9 +1091,9 @@ fn format() {
     let t2 = format!("{:?}", data.iter().format("--"));
     assert_eq!(t2, ans2);
 
-    let dataf = [1.1, 2.71828, -22.];
+    let dataf = [1.1, 5.71828, -22.];
     let t3 = format!("{:.2e}", dataf.iter().format(", "));
-    assert_eq!(t3, "1.10e0, 2.72e0, -2.20e1");
+    assert_eq!(t3, "1.10e0, 5.72e0, -2.20e1");
 }
 
 #[test]