Links being changed causing hash to not be found

[robertlove]

I have the following link:

<a href="https://docs.q-ctrl.com/control-operations#mølmer-sørensen-drive">Mølmer-Sørensen unitary</a>

And the following heading on the /control-operations page:

<h2 id="mølmer-sørensen-drive">Mølmer-Sørensen Drive</h2>

The link works. However, HTML Proofer gives the following error:

- ./_site/control-library.html
  *  External link https://docs.q-ctrl.com/control-operations#m%C3%B8lmer-s%C3%B8rensen-drive failed: https://docs.q-ctrl.com/control-operations exists, but the hash 'm%C3%B8lmer-s%C3%B8rensen-drive' does not

Note that ø is being changed to %C3%B8 - which means it's now looking for #m%C3%B8lmer-s%C3%B8rensen-drive instead of #mølmer-sørensen-drive.