BUG - Multine title of level 1 or 2 - Wrong numbers of "decorators"

[projetmbc]

Here is a code that does not work with version 1.1.0, the public one.

from markdownify import markdownify as md

print(
    md(
        '<h1>Multiline title is allowed!</br>Section 1.2</h1>',
    )
)

This prints

Multiline title is allowed!Section 1.2
======================================

instead of

Multiline title is allowed!
Section 1.2
===========================