Bug#973167: ufonormalizer: FTBFS: dh_auto_test: error: pybuild --test -i python{version} -p "3.9 3.8" returned exit code 13

[Matthias Klose]

Control: forwarded -1 
https://github.com/unified-font-object/ufoNormalizer/issues/73

deprecated features in Python 3.4 ...

there's a proposal to re-introduce the deprecated Data class to work around it.