Unsupported unicode characters exist in two styles that can cause issues for some XML parsers

[mdmower]

These two styles have unsupported unicode characters:

https://github.com/citation-style-language/styles/blob/e328d44b6c1e91f33cf36666bc718141be7d8062/journal-of-the-marine-biological-association-of-the-united-kingdom.csl#L441

https://github.com/citation-style-language/styles/blob/e328d44b6c1e91f33cf36666bc718141be7d8062/museum-national-dhistoire-naturelle.csl#L195