Add experimental Spotify install.

[Gadgetoid]

This installs Spotify from Git. Also fixes an issue with the Mopidy config not resetting to default.

[helgibbons]

I'm not having any luck getting Spotify working with this PR - getting this error in Iris:

I tried compiling / installing gst-plugins-spotify as described here: https://github.com/mopidy/mopidy-spotify#dependencies but I'm still getting that message.

[Gadgetoid]

Login credentials added into the config file and such?

[helgibbons]

Yep - credentials entered and enabled = true set in /etc/mopidy/mopidy.conf

sudo mopidy config says this:

[Gadgetoid]

Weird, I wonder what the particular self check is that prompted this.

Perhaps try some of the steps listed here: https://docs.mopidy.com/en/latest/troubleshooting/

Could be related to? mopidy/mopidy-spotify#202 (comment) I don't know if it's disabled when login fails.

Could be a missing dependency, or

[helgibbons]

aha!

May 19 11:53:26 testpi mopidy[504]: INFO [MainThread] mopidy.ext Disabled extension spotify: Mopidy>=3.4.0 required, but found Mopidy 3.1.1 at /usr/lib/python3/dist-packages

[Gadgetoid]

Ooof, pip install of Mopidy overriding the apt package. This tripped me up too.

[helgibbons]

Working! I needed to

• fix the apt sources so I could update Mopidy to the latest
• build gst-plugins-spotify as described here. The build kept falling over on a 3B+, I eventually had to do it from a Pi 4.
• generate a new ID / secret and update them in /etc/mopidy/mopidy.conf (for some reason)