ssh: Migrate ssh-hardening to use the new collection

This patch should migrate to the new devsec.hardening collection, which
failed in a previous attempt[1] due to a bug in the collection. It
should now be updated and working with Ansible 2.9.

[1]: 234c93c2

This reverts commit 629f2ebf.

requirements.yml

 ---
-
-- src: dev-sec.ssh-hardening
-  version: 9.7.0
+collections:
+- name: devsec.hardening
+  version: 7.4.0

ssh.yml

@@ -18,8 +18,10 @@
 #
 
 - hosts: ssh
+  collections:
+    - devsec.hardening
   roles:
     - sys-upgrade
-    - role: dev-sec.ssh-hardening
+    - role: devsec.hardening.ssh_hardening
       become: true
     - ssh