Create apt preferences for unstable repo

roles/essential-tools/files/99pin-unstable

@@ -0,0 +1,7 @@
+Package: *
+Pin: release a=testing
+Pin-Priority: 900
+
+Package: *
+Pin: release a=unstable
+Pin-Priority: 10

roles/essential-tools/tasks/main.yml

@@ -3,14 +3,20 @@
   apt_repository:
     repo: deb http://deb.debian.org/debian unstable main non-free-firmware non-free contrib
     state: present
-    update_cache: true
     filename: debian-unstable
 
+- name: Create apt preferences file for unstable repo
+  become: yes
+  copy:
+    src: "{{ role_path }}/files/99pin-unstable"
+    dest: "/etc/apt/preferences.d/"
+
 - name: Install essential tools
   become: yes
   apt:
     state: latest
     install_recommends: false
+    update_cache: true
     name:
       - thunar
       - firefox