user/listenbrainz-mpd: update to 2.5.1

[JetpackJackson]

Checklist

Before this pull request is reviewed, certain conditions must be met.

The following must be true for all changes:

• I have read CONTRIBUTING.md
• I acknowledge that overtly not following the above or the below will result in my pull request getting closed

The following must be true for template/package changes:

• I have read Packaging.md
• I have built and tested my changes on my machine

The following must be true for new package submissions:

• I will take responsibility for my template and keep it up to date

[wezm]

2.5.1 is out now.

[JetpackJackson]

Ah shoot, I thought I had done that version when I checked for updates recently. Would you prefer me to do a new PR, or should I force-push into this one?