RFE: Convert update notes to plaintext before sending email

[oturpe]

Currently, Bodhi's notification emails look like this:

       Bugs: 2156900 - None
      Notes: Automatic update for systemd-253~rc2-2.fc38.  ##### **Changelog**
           : ``` * Thu Feb  2 2023 Michael Catanzaro
           :[<mcatanzaro@redhat.com> - 253~rc2-2 - Shorten shutdown
           : timeout to 45 s * Thu Feb  2 2023 Zbigniew
           : Jędrzejewski-Szmek <zbyszek@in.waw.pl>) - 253~rc2-1 -
           : Version 253~rc2 - Sysusers fixup (rhbz#2156900) +
           : other small changes * Thu Feb  2 2023 Yaakov Selkowitz
           : <yselkowi@redhat.com> - 253~rc1-5 - Build with xen
           : only on Fedora  ```
  Submitter: zbyszek
  Submitted: 2023-02-02 20:11:41.724093
   Comments: bodhi - 2023-02-02 20:11:41.727324 (karma 0)
             This update was automatically created

  https://bodhi.fedoraproject.org/updates/FEDORA-2023-2ac77d299f

Observe that the Notes section is quite corrupted,
with visible Markdown formatting
and line breaks that were originally present in the package's changelog missing.

For readability, before sending update notification email,
Notes should be converted to plaintext, retaining original linebreaks.

This issue has been discussed in the Fedora devel mailing list.

[mattiaverga]

With the proposed PR the output would be:

>>> up = m.Update.get('FEDORA-2023-2ac77d299f')
>>> print(up)
================================================================================
     FEDORA-2023-2ac77d299f
================================================================================
    Release: Fedora 38
     Status: stable
       Type: unspecified
   Severity: unspecified
      Karma: 0
   Critpath: True
       Bugs: 2156900 - /usr/lib/sysusers.d/basic.conf:9: Conflict with earlier
             configuration for user 'root', ignoring line.
      Notes: Automatic update for systemd-253~rc2-2.fc38.
             Changelog
             * Thu Feb  2 2023 Michael Catanzaro <mcatanzaro@redhat.com> -
             253~rc2-2
             - Shorten shutdown timeout to 45 s
             * Thu Feb  2 2023 Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
             - 253~rc2-1
             - Version 253~rc2
             - Sysusers fixup (rhbz#2156900) + other small changes
             * Thu Feb  2 2023 Yaakov Selkowitz <yselkowi@redhat.com> -
             253~rc1-5
             - Build with xen only on Fedora
  Submitter: zbyszek
  Submitted: 2023-02-02 20:11:41.724093
   Comments: bodhi - 2023-02-02 20:18:12.944264 (karma 0)
             This update has been submitted for stable by bodhi
             bodhi - 2023-02-02 20:17:25.043341 (karma 0)
             This update's test gating status has been changed to 'ignored'.
             bodhi - 2023-02-02 20:17:24.775290 (karma 0)
             This update's test gating status has been changed to 'waiting'.
             bodhi - 2023-02-02 20:11:41.727324 (karma 0)
             This update was automatically created

  https://bodhi-dev.example.com/updates/FEDORA-2023-2ac77d299f
>>> 

Thoughts?

[oturpe]

Looks great to me!