syntax fix

common/prometheus-node/tasks/main.yml

@@ -2,10 +2,10 @@
 # Pakete installieren
 - name: pakete installieren
   apt:
-    pkg: "{{ item }}"
-    update_cache: yes
-    state: installed
-  with_items:
+    name: "{{ packages }}"
+    state: present
+  vars:
+    packages:
     - prometheus-node-exporter
 
 - name: remove old directories