Use Slack repos

Fuck you for making me install a package first, Slack
Had to reverse engineer this one out of the apt lists
Just list the goddamn

roles/desktop-common/tasks/packages.yml

@@ -27,6 +27,7 @@
       repo: "{{ item }}"
     loop:
       # Debs
+      - "deb https://packagecloud.io/slacktechnologies/slack/debian/ jessie main" # Slack
       - "deb http://repository.spotify.com stable non-free" # Spotify
       - "deb https://apt.syncthing.net/ syncthing stable" # Syncthing
       - "deb https://download.mono-project.com/repo/ubuntu vs-bionic main" # Monodevelop
@@ -163,6 +164,7 @@
         - retroarch
         - rofi
         - scrot # For scripted screenshots
+        - slack-desktop
         - spotify-client
         - steam-installer
         - syncthing-gtk
@@ -207,7 +209,6 @@
       deb: "{{ item }}"
     loop:
       - "https://dl.discordapp.net/apps/linux/0.0.12/discord-0.0.12.deb"
-      - "https://downloads.slack-edge.com/linux_releases/slack-desktop-4.8.0-amd64.deb"
       - "https://github.com/MultiMC/MultiMC5/releases/download/0.6.8/multimc_1.4-1.deb"
       - "https://zoom.us/client/latest/zoom_amd64.deb"
     # We ignore errors here in case we have a more up-to-date package on the target machine and/or face a URL timeout