Add conversion support for <q> tags

[colinrobinsonuib]

From this issue: #216

https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/q

HTML that looks like this:

Here is <q>A Quote</q> from someone.

should be rendered as:

Here is “A Quote“ from someone.

Technically, the quotes rendered from <q> are dependent on the browser lang attribute

https://developer.mozilla.org/en-US/docs/Web/CSS/quotes#specifications

<ul>
  <li lang="fr">
    <q>Ceci est une citation française.</q>
  </li>
  <li lang="de">
    <q>Dies ist ein deutsches Zitat</q>
  </li>
  <li lang="en">
    <q>This is an English quote.</q>
  </li>
</ul>

- «Ceci est une citation française.»
- „Dies ist ein deutsches Zitat“
- “This is an English quote.”

But this PR uses simple straight quotes

[chrispy-snps]

Thank you @colinrobinsonuib! Can you please also add a unit test in tests/test_conversions.py?

[chrispy-snps]

Thank you for your contribution @colinrobinsonuib!