snap: Update to 28.0

[achow101]

No description provided.

[maflcko]

The guix builds require glibc 2.31 (bitcoin/bitcoin#29987 ). I am not sure how snap build works internally, but I think the tests are just run on the host system, using the host glibc. So you may have to bump .cirrus.yml

[achow101]

So you may have to bump .cirrus.yml

I tried. Ubuntu >=20 can't install snapcraft to build the snap. Apparently snapcraft can't be installed in docker?

[maflcko]

Yeah, it may require a docker-in-docker hack. An alternative may be to use a "real" vm, instead of a container. You could try by replacing container: image: ... with something like:

  compute_engine_instance:
    image_project: ubuntu-os-cloud
    image: family/ubuntu-2204-lts

[achow101]

There appear to be GitHub actions for building a snap and pushing it to the snap store, perhaps we should switch to those. Would also simplify the release process to cut out launchpad.

[maflcko]

Snaps can be compromised when launchpad is compromised (obviously). However, when using GHA to push the image, a snap can also be compromised by GHA. No strong opinion, but I wanted to mention it.