EPUB: Get page number from epub:type="pagebreak" aria-label

In addition to title.

https://forums.zotero.org/discussion/131458/epub-page-number-isnt-recognized-by-zotero
(cherry picked from commit e1a0992)

Author: AbeJellinek

src/dom/epub/lib/page-mapping.ts

@@ -47,7 +47,7 @@ class PageMapping {
 		return mapping;
 	}
 
-	static readonly VERSION = 13;
+	static readonly VERSION = 14;
 
 	private readonly _tree = new BTree<PersistentRange, string>(
 		undefined,
@@ -290,7 +290,9 @@ const MATCHERS: Matcher[] = [
 
 	{
 		selector: '[*|type="pagebreak"]',
-		extract: el => el.getAttribute('title') ?? undefined
+		extract: el => el.getAttribute('title')
+			?? el.getAttribute('aria-label')
+			?? undefined
 	}
 ];