fix: corrected duplicate hyperlink

[ethan-moss]

Description:

A very small PR to fix a duplicate URL in the bibliography:

• Minor change in references.bib: corrected duplicate URL to right address.

Checklist:

• [X] Include a contribution summary: A clear and concise description of the changes proposed.
• [X] I have read the CONTRIBUTING.md guidance for raising pull requests
• [X] This pull-request meets the accessibility guidance provided in the contributing guidance.
• [X] Please detail any accessibility errors or alerts discovered on testing within the pull-request.

Referencing issues and pull requests

Fixes #34