Adding the challenge 0403

0403/os_other.go

@@ -0,0 +1,11 @@
+//go:build !unix
+
+package db0403
+
+import "os"
+
+func createFileSync(file string) (*os.File, error) {
+	return os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0o644)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/