Accessing element.ref was removed in React 19. ref is now a regular prop. It will be removed from the JSX Element type in a future release.

**Description**
It seems like blocknote is misusing the element.ref which has now been changed to a regular prop.

**To Reproduce**

1. Use blocknote with nextjs 15 and react 19.
2. Create a custom block.

**Misc**
- Node version: v18.19.1
- Package manager: bun
- Browser: chrome
