CI: Update gsignond build process

2 jobs for master in 4 minutes and 31 seconds
Status Job ID Name Coverage
  Build
passed #96129189
build_amd64

00:02:41

 
  Test
failed #96129190
test_amd64

00:01:50

 
Name Stage Failure
failed
test_amd64 Test
Processing triggers for systemd (229-4ubuntu21.4) ...
$ git clone https://gitlab.com/accounts-sso/gsignond.git
Cloning into 'gsignond'...
$ cd gsignond
$ meson build --prefix=/usr -Ddebug=true
Error during basic setup:

[Errno 2] No such file or directory: '/builds/accounts-sso/libgsignon-glib/gsignond/build'
ERROR: Job failed: exit code 1