fix(onboarding): Escape newline in go-fiber snippet (#71986)

static/app/gettingStartedDocs/go/fiber.tsx

@@ -36,7 +36,7 @@ if err := sentry.Init(sentry.ClientOptions{
   // We recommend adjusting this value in production,
   TracesSampleRate: 1.0,
 }); err != nil {
-  fmt.Printf("Sentry initialization failed: %v\n", err)
+  fmt.Printf("Sentry initialization failed: %v\\n", err)
 }
 
 // Later in the code