Links with more than 6 pairs of parenthesis aren't parsed correctly #896
Description
Hi there,
I'm working with URIs that contain rison encoded data, which uses parenthesis for serializing json-like objects and arrays.
This can lead to URIs such as this one.
While it looks kind of odd, it's still a valid URI as far I can tell.
However, when I tried putting this into a mdbook, it simply rendered the markdown line as text.
Example input:
[1](https://rust.org/something%3A())
[2](https://rust.org/something%3A(()))
[3](https://rust.org/something%3A((())))
[4](https://rust.org/something%3A(((()))))
[5](https://rust.org/something%3A((((())))))
[6](https://rust.org/something%3A(((((()))))))
[7](https://rust.org/something%3A((((((())))))))
[8](https://rust.org/something%3A(((((((()))))))))
[9](https://rust.org/something%3A((((((((())))))))))
[10](https://rust.org/something%3A(((((((((()))))))))))
[11](https://rust.org/something%3A((((((((((())))))))))))
[12](https://rust.org/something%3A(((((((((((()))))))))))))
[13](https://rust.org/something%3A((((((((((((())))))))))))))
[14](https://rust.org/something%3A(((((((((((((())))))))))))))) pulldown_cmark::html::push_html's output:
<p><a href="https://rust.org/something%3A()">1</a><br />
<a href="https://rust.org/something%3A(())">2</a><br />
<a href="https://rust.org/something%3A((()))">3</a><br />
<a href="https://rust.org/something%3A(((())))">4</a><br />
<a href="https://rust.org/something%3A((((()))))">5</a><br />
<a href="https://rust.org/something%3A(((((())))))">6</a><br />
[7](https://rust.org/something%3A((((((())))))))<br />
[8](https://rust.org/something%3A(((((((()))))))))<br />
[9](https://rust.org/something%3A((((((((())))))))))<br />
[10](https://rust.org/something%3A(((((((((()))))))))))<br />
[11](https://rust.org/something%3A((((((((((())))))))))))<br />
[12](https://rust.org/something%3A(((((((((((()))))))))))))<br />
[13](https://rust.org/something%3A((((((((((((())))))))))))))<br />
[14](https://rust.org/something%3A(((((((((((((()))))))))))))))</p>