fix(std): math round (amber-lang#426)

src/std/math.ab

@@ -6,7 +6,11 @@ pub fun sum(list: [Num]): Num {
 /// Returns the number rounded to the nearest integer
 #[allow_absurd_cast]
 pub fun round(number: Num): Num {
-    return unsafe $LC_ALL=C printf "%0.f" "{number}"$ as Num
+    if number > 0 {
+        return unsafe $echo "({number}+0.5)/1" | bc$ as Num
+    }
+
+    return unsafe $echo "({number}-0.5)/1" | bc$ as Num
 }
 
 /// Returns the largest integer less than or equal to the number