Upgrade ansible-role-backup_borg (v1.4.4-2.1.4-1 -> v1.4.4-2.1.6-1)

Pulls in borgmatic 2.1.6, fixing the 2.1.4 JSON parsing regression
(borgmatic-collective/borgmatic#1294) where warnings on stderr, such as
OpenSSH post-quantum key exchange notices, broke parsing of borg's JSON
output and failed the backup run.

Fixes #5188

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

requirements.yml

@@ -4,7 +4,7 @@
   version: v1.0.0-7
   name: auxiliary
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-backup_borg.git
-  version: v1.4.4-2.1.4-1
+  version: v1.4.4-2.1.6-1
   name: backup_borg
 - src: git+https://github.com/mother-of-all-self-hosting/ansible-role-cinny.git
   version: v4.12.3-0