deployment: Set permissions of pki secret volume
deployment: Set permissions of pki secret volume

The PKI folder should only be readable by root. Set the permissions to
0400.

This removes the following warnings from the logs:
  WARNING: file '/etc/openvpn/pki/private.key' is group or others accessible
  WARNING: file '/etc/openvpn/pki/ta.key' is group or others accessible

pieterlange/kube-openvpn