fix: install git as required by Ansible builtin Git module

tasks/install_ibmsp_client.yml

@@ -62,6 +62,10 @@
 
 - name: install check-backup scripts
   block:
+    - name: install Git (required by Ansible builtin Git module)
+      apt:
+        name: "git"
+        state: latest
     - name: check out check-backup Git repo
       git:
         repo: "git@git.slub-dresden.de:slub-referat-2-3/check-backup.git"