Should be == instead of =.

[BrendanKKrueger]

PR Summary

Fix a typo that somehow slipped in.

PR Checklist

• Any changes to code are appropriately documented.
• Code is formatted.
• Install test passes.
• Docs build.
• If preparing for a new release, update the version in cmake.

[BrendanKKrueger]

@Yurlungur, I found a typo and tried building things to make sure there weren't others. I get errors with Catch2, but it's not clear if there's a problem with the code or my environment or other. When you get a chance, would you mind trying to build and see if it works or not?

[Yurlungur]

whoopsie thanks for the fix

[BrendanKKrueger]

whoopsie thanks for the fix

I'm pretty sure I put that typo in, so it's only fair that I fix it :-)