Refactoring (#17)

Reviewed-on: #17
Co-authored-by: phoenix <kundeng00@pm.me>
Co-committed-by: phoenix <kundeng00@pm.me>

internal/version/version.go

@@ -0,0 +1,17 @@
+package version
+
+import "fmt"
+
+var (
+	Version   = "dev"
+	BuildTime = "unknown"
+	Commit    = "unknown"
+	GoVersion = "unknown"
+)
+
+func String() string {
+	return fmt.Sprintf(
+		"Version: %s\nBuild Date: %s\nCommit: %s\nGo Version: %s",
+		Version, BuildTime, Commit, GoVersion,
+	)
+}