Update supported browser versions

[ajwild]

• I've updated the versions to 1 year before the next release month, so in this case they are the most recent versions from June 2024 ready for the July 2025 release. If there's ever a difference between the Chrome and Edge version then I would make Edge match the Chrome version even if it ends up being 51 weeks old. Edge seems to have the an aggressive update policy so I doubt this will be an issue.
• I've dropped iOS Safari because it's always the same version as regular Safari, and we don't list Chrome for Android separately (even though Can I use... lists these separately).
• I've dropped Opera because we only had 10 of 4000 users on TrackJS using it, it's based on Chrome (or at least the same engines), it's generally up-to-date versions that we see, and I don't think anyone is actively developing or testing with it.