Add infinite loop / memory leak issue test

[marshallino16]

Hi,

Calling parse method MarkdownParser().parse() with the given HTML, containing an unclosed tag :

<p align="center">
            <img src="Logo.png" width="278" max-width="90%" alt=“Ink” />
        </p>

        <p align="center">
            <img src="https://img.shields.io/badge/Swift-5.2-orange.svg" />
            <a href="https://swift.org/package-manager">
                <img src="https://img.shields.io/badge/swiftpm-compatible-brightgreen.svg?style=flat" alt="Swift Package Manager" />
            </a>
             <img src="https://img.shields.io/badge/platforms-mac+linux-brightgreen.svg?style=flat" alt="Mac + Linux" />
            <a href="https://twitter.com/johnsundell">
                <img src="https://img.shields.io/badge/[email protected]?style=flat" alt="Twitter: @johnsundell" />
            </a>
        </p>


        # Hellow
        ## Hellowww
        * a
        * b
        * c

        <p

Results an infinite loop / memory leak.

Any idea how to prevent that?

Thanks