misc/deb_unstable: Added updating of apt cache using handler

roles/misc/deb_unstable/meta/main.yml

@@ -1,3 +1,6 @@
 ---
 
 allow_duplicates: no
+
+dependencies:
+  - misc/handlers

roles/misc/deb_unstable/tasks/main.yml

@@ -7,6 +7,7 @@
     group: root
     mode: "u=rw,g=r,o=r"
     content: "deb http://deb.debian.org/debian/ unstable main"
+  notify: update apt cache
 
 - name: Restrict unstable for apt
   copy:
@@ -18,3 +19,4 @@
       Package: *
       Pin: release a=unstable
       Pin-Priority: 90
+  notify: update apt cache