examples: enhance the call_v_from_python example, with a fn accepting 2 f64 params (#13480)

examples/call_v_from_python/test.v

@@ -1,6 +1,13 @@
 module test
 
+import math
+
 [export: 'square']
 fn square(i int) int {
 	return i * i
 }
+
+[export: 'sqrt_of_sum_of_squares']
+fn sqrt_of_sum_of_squares(x f64, y f64) f64 {
+	return math.sqrt(x * x + y * y)
+}