Inline style injection used in v11 not compatible with Content-Security-Policy

FYI, using react-toastify v11 with CSP response headers causes the following errors...

```
Refused to apply inline style because it violates the following Content Security Policy directive: "style-src 'self'". Either the 'unsafe-inline' keyword, a hash ('sha256-...'), or a nonce ('nonce-...') is required to enable inline execution.
```

Using the undocumented `unstyled` import seems to resolve the issue, but this feels brittle to me. It would be great if you could explore other options for injecting the stylesheet.