Issue #353: Improvements to logo

[athowes]

Description

This PR closes #353. It uses the old colour scheme, makes the figure bigger, needs to use whitespace around logo for that reason, gets rid of code that does nothing about fonts.

Checklist

• My PR is based on a package issue and I have explicitly linked it.
• I have included the target issue or issues in the PR title in the for Issue(s) issue-numbers: PR title
• I have read the contribution guidelines.
• I have tested my changes locally.
• I have added or updated unit tests where necessary.
• I have updated the documentation if required.
• My code follows the established coding standards.
• I have added a news item linked to this PR.
• I have reviewed CI checks for this PR and addressed them as far as I am able.

[seabbs]

Can you look into use_logo again? In particular I see these are missing: https://github.com/epinowcast/primarycensoreddist/tree/main/pkgdown/favicon

[athowes]

Can you look into use_logo again? In particular I see these are missing: https://github.com/epinowcast/primarycensoreddist/tree/main/pkgdown/favicon

Done

[seabbs]

Nice. LGTM