Extra line breaks between status groups of a "message/delivery-status" mime part results in missing status group.

[daikoz]

Describe the bug
When parsing a "message/delivery-status" body part, having an extra line break after the first group results in the 2nd group not being parsed into the MessageDeliveryStatus.StatusGroups property.

Platform:

• OS: Windows & Linux
• .NET Runtime: core 9
• .NET Framework: .Net Core 9
• MimeKit Version: 4.13.0

To Reproduce
Steps to reproduce the behavior:

1. Run the code snippet (sample file attached). test.zip
2. StatusGroups should contain all header, but the group contain only Reporting-MTA.

Expected behavior
StatusGroups should contain all header, but the group contain only Reporting-MTA.

Code Snippets
see test.zip. it contain the mail and the test code.

[jstedfast]

There's no extra blank line. This was actually an issue with buffering/state-tracking that just so happened to decide it was at EOS after the first group.

[jstedfast]

Anyways, should be fixed now.