test(pillar): add `ssh-rsa` Kitchen workaround on Arch Linux [skip ci]

Need this on Arch Linux to avoid the `kitchen verify` failure; see:

* https://gitlab.com/saltstack-formulas/infrastructure/salt-image-builder/-/commit/cb6781a2bba9

test/integration/default/files/_mapdata/arch-base-latest.yaml

     AcceptEnv: LANG LC_*
     ChallengeResponseAuthentication: 'no'
     PrintMotd: 'no'
+    PubkeyAcceptedAlgorithms: "+ssh-rsa"
     Subsystem: sftp /usr/lib/openssh/sftp-server
     UsePAM: 'yes'
     X11Forwarding: 'yes'

test/salt/pillar/default.sls

   {%- if grains.os != "OpenBSD" %}
   UsePAM: 'yes'
   {%- endif %}
+  {#- Need this on Arch Linux to avoid the `kitchen verify` failure as mentioned above; see: #}
+  {#- * https://gitlab.com/saltstack-formulas/infrastructure/salt-image-builder/-/commit/cb6781a2bba9 #}
+  {%- if grains.os == "Arch" %}
+  PubkeyAcceptedAlgorithms: "+ssh-rsa"
+  {%- endif %}
 
 ssh_config:
   Hosts: