Description

Heading blocks can contain newlines (shift+enter) but ToC block won't show them:

Step-by-step reproduction instructions

1. Add Table of Contents block
2. Add heading block
3. Enter text, create new line within heading (shift+enter), and enter more text
4. See how ToC block doesn't contain the newline

Screenshots, screen recording, code snippet

I got around the problem by adding a space before newline:

Environment info

• Gutenberg: v13.3.0-rc.1

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

No

FYI @ZebulanStanphill