textproc/py-ntc-templates: Update to 3.2.0

• Switch to the PEP-517 build framework and remove the setuptools workaround.

• Also convert "do-test" target to USE_PYTHON=pytest while I'm here.

Changelog:

https://github.com/networktocode/ntc-templates/compare/v3.1.0...v3.2.0

MFH: No (PEP-517 support not present in the 2023Q1 branch)