Specify build system requirements

[buberdds]

Did something change in Python stack? We are not able to use towncrier in CI (sample: https://github.com/oasisprotocol/explorer/actions/runs/10107648176/job/27951924406?pr=1491)

The error says that we are missing project metadata which relates to PEP 631. After adding metadata

[project]
    name = "towncrier"
    description = "Building newsfiles for your project."
    version="19.2.0"
    readme = "README.rst"
    license = { text = "MIT License" }

I was not able to build the project.

I ended up with specifying build system requirements (PEP 518). This is what towncrier was using before switching to hatchling twisted@65d25e0#diff-50c86b7ed8ac2cf95bd48334961bf0530cdc77b5a56f852c5c61b89d735fd711L80.

I am not 100% what is the best way to tackle this in our 4-5yr old fork, but I am able to build and install towncier locally with this change.

[buberdds]

The error is not happening anymore in CI. Will keep PR for now if problems occur again.