slapos_pdm: fix unused-variable for pylint

master/bt5/slapos_pdm/SkinTemplateItem/portal_skins/slapos_pdm/HostingSubscription_getNewerSofwareRelease.py

 hosting_subscription = context
-portal = context.getPortalObject()
 
 software_instance = hosting_subscription.getPredecessorValue()
 if not software_instance:

master/bt5/slapos_pdm/SkinTemplateItem/portal_skins/slapos_pdm/UpgradeDecision_notifyDelivered.py

@@ -18,8 +18,6 @@ software_release = context.UpgradeDecision_getSoftwareRelease()
 software_product_title = software_release.getAggregateTitle(
                                portal_type="Software Product")
 
-reference = context.getReference()
-
 mapping_dict = {
   'software_product_title': software_product_title,
   'software_release_name': software_release.getTitle(),