Book details: Fix a regression in the previous release that broke the right click search the internet function

Fixes #1842090 ["Search the internet for..." right-click options fail](https://bugs.launchpad.net/calibre/+bug/1842090)

src/calibre/gui2/__init__.py

@@ -1145,6 +1145,8 @@ def open_url(qurl):
 
 
 def safe_open_url(qurl):
+    if isinstance(qurl, string_or_bytes):
+        qurl = QUrl(qurl)
     if qurl.scheme() in ('', 'file'):
         path = qurl.toLocalFile()
         ext = os.path.splitext(path)[-1].lower()[1:]