Fix F841 local variable 'setup' is assigned to but never used

Author: xispa

src/senaite/core/upgrade/v02_04_000.py

@@ -30,7 +30,6 @@
 @upgradestep(product, version)
 def upgrade(tool):
     portal = tool.aq_inner.aq_parent
-    setup = portal.portal_setup
     ut = UpgradeUtils(portal)
     ver_from = ut.getInstalledVersion(product)