Log message:
py-validate-pyproject: added version 0.7.1

With the approval of PEP 517 and PEP 518, the Python community shifted towards
a strong focus on standardisation for packaging software, which allows more
freedom when choosing tools during development and make sure packages created
using different technologies can interoperate without the need for custom
installation procedures.

This shift became even more clear when PEP 621 was also approved, as a
standardised way of specifying project metadata and dependencies.

validate-pyproject was born in this context, with the mission of validating
pyproject.toml files, and make sure they are compliant with the standards and
PEPs. Behind the scenes, validate-pyproject relies on JSON Schema files, which,
in turn, are also a standardised way of checking if a given data structure
complies with a certain specification.