ComicInfo.xml "Volume" element seems wrong, possibly should be "Number" instead?

Bug report

Environment (please complete the following information):

Description	Data
Manga-py version	1.29.5

To Reproduce:

Steps to reproduce the behavior:

1. Download a series with a volume name of “67-1” (an example)
2. ComicInfo.xml looks like this in the first few lines:

<?xml version="1.0"?>
<ComicInfo xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Title>blah_blah</Title>
  <Volume>67-1</Volume>
  <PageCount>20</PageCount>
.....

1. Trying to use komga to analyze the metadata of the cbz that contains it throws an error:

Cannot deserialize value of type `java.lang.Integer` from String "67-1": not a valid Integer value

1. Searching for a definition of the comicinfo xml format led me to this gist. Seems that Volume should only be an Int. Number is freeform. In this case, I think Number is perhaps more apt since it is a semi-freeform value like “67-1” or “66”, depending on the manga site and how they format volume names (manga-py appears to convert “67.1” to “67-1” already so filenames are better).
2. In download_methods.py, I changed the following:

--- download_methods_old.py	2021-04-27 20:25:39.977518478 -0700
+++ download_methods.py	2021-04-27 20:25:23.633284790 -0700
@@ -159,7 +159,7 @@
     def _book_info_xml(self):
         comic_info = ComicInfo()
 
-        comic_info.volume(self.provider.get_chapter_index())
+        comic_info.number(self.provider.get_chapter_index())
         comic_info.title(self.provider.name)
         comic_info.pages(self.__pages_cache)
         comic_info.page_count(str(len(self.__pages_cache)))

Output xml is now:

<?xml version="1.0"?>
<ComicInfo xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Title>blah_blah</Title>
  <Number>67-1</Number>
  <PageCount>20</PageCount>
.....

1. With the change komga parses the xml happy, and even seems to get the sorting (individual cbz “book” number) more correct.

[dropwhile]

Do you remember on which site it happened?

https://bato [.] to/series/83648/boku-no-hero-academia-official (url munged a bit to not link directly)

[1271]

Thank you for your issue, I’ll think about how to fix it