Update install.yml to fix fresh Debian install.

Fresh install was failing if the zerotier repo did not exist. Changed the initial check to check the existence of the zerotier repo file.

tasks/install.yml

@@ -23,17 +23,15 @@
   # Debian variants
 - block: # Add zerotier repo and it's gpg key if not already done.
   - name: Check if zerotier is already installed
-    package:
-      name: zerotier-one
-      state: present
-    check_mode: true
+    stat:
+      path: /etc/apt/sources.list.d/zerotier.list
     register: zerotier_repo
 
   - name: Install zerotier
     shell: curl -s 'https://pgp.mit.edu/pks/lookup?op=get&search=0x1657198823E52A61' | gpg --import && \
                if z=$(curl -s 'https://install.zerotier.com/' | gpg); then echo "$z" | sudo bash; fi
     register: zerotier_repo
-    when: zerotier_repo.changed
+    when: zerotier_repo.stat.exists == False
   tags:
   - installation
   - repositories