Remove empty format precision specifier

A format precision specifier consisting of a dot and no number actually does nothing and has no specified meaning. Currently this is silently ignored, but it may turn into a warning or error.

See rust-lang/rust#131159 and rust-lang/rust#136638

Author: hkBst

src/bin/024.rs

@@ -12,5 +12,5 @@ fn main() {
         .iter()
         .map(|&(p, q)| (q as f32) / (p as f32))
         .sum::<f32>();
-    println!("{:.?}", result);
+    println!("{:?}", result);
 }