Added activation spec changes to changelog

Changes that happened on the activation package spec file
were not part of the package changelog generated by
helper/update_changelog.py

Makefile

@@ -33,6 +33,7 @@ sle15_activation: check
 	# update rpm changelog using reference file
 	helper/update_changelog.py \
 		--since package/suse-migration-sle15-activation.changes.ref \
+		--from package/suse-migration-sle15-activation-spec-template \
 		--from grub.d --utc > \
 		dist/suse-migration-sle15-activation.changes
 	helper/update_changelog.py \

helper/update_changelog.py

@@ -1,7 +1,7 @@
 #!/usr/bin/python3
 """
 usage: update_changelog (--since=<reference_file>|--file=<reference_file>)
-            [--from=<path>]
+            [--from=<path>...]
             [--utc]
 
 arguments:
@@ -72,7 +72,8 @@
     if latest_date:
         git_arguments.append('--since="{0}"'.format(latest_date))
     if arguments.get('--from'):
-        git_arguments.append(arguments.get('--from'))
+        for source_repo in arguments.get('--from'):
+            git_arguments.append(source_repo)
 
     process = subprocess.Popen(
         git_arguments, stdout=subprocess.PIPE