fix all ansible-lint yaml errors (except for line-length)

playbooks/roles/apt_update_and_upgrade/tasks/main.yaml

@@ -1,15 +1,15 @@
 - name: update, upgrade and potentially reboot
   become: true
   block:
-  - name: apt-get update
-    ansible.builtin.apt:
-      update-cache: true
+    - name: apt-get update
+      ansible.builtin.apt:
+        update-cache: true
 
-  - name: apt-get dist-upgrade
-    ansible.builtin.apt:
-      upgrade: dist
-    register: apt_update_and_upgrade__upgrade_result
+    - name: apt-get dist-upgrade
+      ansible.builtin.apt:
+        upgrade: dist
+      register: apt_update_and_upgrade__upgrade_result
 
-  - name: reboot, after package upgrade
-    ansible.builtin.reboot:
-    when: apt_update_and_upgrade__upgrade_result.changed
+    - name: reboot, after package upgrade
+      ansible.builtin.reboot:
+      when: apt_update_and_upgrade__upgrade_result.changed