Update book_manager.py to fix #286 (#287)

Implement the fix mentioned in
https://github.com/calibrain/calibre-web-automated-book-downloader/issues/286

Note however that I have 0% success with downloads with 0.2.2 even with
this change.

book_manager.py

@@ -241,7 +241,7 @@ def _parse_book_info_page(soup: BeautifulSoup, book_id: str) -> BookInfo:
     book_info = BookInfo(
         id=book_id,
         preview=preview,
-        title=divs[7].next.strip(),
+        title=divs[7].text.strip(),
         publisher=divs[11].text.strip(),
         author=divs[9].text.strip(),
         format=format,