This update for rubygem-mail fixes the following issues:

Compatibility fixes:
- Restore conversions for properly encoded non-binary emails.
- Gracefully parse certain invalid Content-Type headers. (rafbm)

Bug fixes:
- Fix transfer encoding when message encoding is blank. (bsc#1156721)
- Fix 7bit/base64 content transfer encoding mismatch. (bsc#1156721)
- Fix UTF-8 attachment filename quoting. (bsc#1156721)
- Fix 'delete_all' using a readonly IMAP connection. (bsc#1156721)

This update was imported from the SUSE:SLE-15:Update update project.