Follow up to #4598

Description

#4598 missed a reference to the Titillium Web font, which was previously provided by Google Web Fonts.

Motivation and Context

Clean up. We shouldn't reference this font anymore. It's not really urgent, as the font will only if there is a @font-face declaration for it somewhere. The swagger-ui-express project still does that in their template, which was how I noticed this: https://github.com/scottie1984/swagger-ui-express/blob/bef977310e04ea415d2510ce52ca2a923a038752/indexTemplate.html#L7

(~~~I'll make~~~ I have made a separate PR to that project to get that line removed: scottie1984/swagger-ui-express#88)

How Has This Been Tested?

Didn't test it to be honest.

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.