Reader broken in Safari 15.x

[tnajdek]

The main problem is that pdf.js officially supports Safari >=16.4. In reality, it sometimes works in Safari 15.x with dev tools open, but most of the time, it doesn't. Additionally, the EPUB view of the reader is currently not compatible with Safari 15.x. I've previously been able to fix this, but I don't believe it's feasible given pdf.js's lack of compatibility.

Therefore, I'm going to explicitly exclude Safari 15 from reader-compatible browsers. The web library will display a warning, similar to what it does for older versions of Safari (See #548).

[tnajdek]

https://forums.zotero.org/discussion/118401/web-library-issues

Here, pdf.js fails to load for a Safari 15 user. The user then attempts to change the color scheme, which triggers the error message report.