Merge branch 'fix-gen-release-notes-unicode' into 'master'

Fix gen_release_notes for unicode input

See merge request !255

LbRelease/python/LbRelease/GenReleaseNotes.py

@@ -274,7 +274,7 @@ Example:
         'merge_requests': git_mrs,
     }
     with open(args.output, 'w') as f:
-        f.write(template.render(context))
+        f.write(template.render(context).encode('utf8'))
     print('Release notes draft written to {}.'.format(args.output))