[TIDY] move when statements, fix whitespace

Having the when condition of a task at the top instead of bottom is
easiert to read. Also some spaces were another whitespace character on
accident.

tasks/borgbackup-Debian.yml

@@ -8,12 +8,12 @@
 # For all other Debian versions, simply install borgbackup
 
 - name: borgbackup - Install borgbackup
-  become: yes
-  ansible.builtin.apt:
-    name: borgbackup
-    state: present
   when:
     - borgbackup_passphrase is defined
     - borgbackup_repo is defined
     - borgbackup_hostname is defined
     - ansible_distribution_release != 'stretch'
+  become: yes
+  ansible.builtin.apt:
+    name: borgbackup
+    state: present