Grammar tests fail too often

[PEZ]

The CI job for running grammar tests fails now and then, like this:

#!/bin/bash -eo pipefail
cd src/calva-fmt/atom-language-clojure
./build-package.sh

Downloading latest Atom release on the stable channel...
dpkg-deb: error: 'atom-amd64.deb' is not a Debian format archive
dpkg: error processing archive atom-amd64.deb (--install):
 dpkg-deb --control subprocess returned error exit status 2
Errors were encountered while processing:
 atom-amd64.deb
Hit:1 http://security.debian.org/debian-security bullseye-security InRelease
Hit:2 http://deb.debian.org/debian bullseye InRelease
Hit:3 http://deb.debian.org/debian bullseye-updates InRelease
Reading package lists... Done
Reading package lists...
Building dependency tree...
Reading state information...
0 upgraded, 0 newly installed, 0 to remove and 108 not upgraded.
Using Atom version:
./build-package.sh: 94: atom: not found
Using APM version:
./build-package.sh: 96: apm: not found
Downloading package dependencies...
./build-package.sh: 102: apm: not found
Running specs...
./build-package.sh: 196: atom: not found

Exited with code exit status 127
CircleCI received exit code 127

It seems that atom.io, which build-package.sh relies on is not super reliable these days.