Fixes DeprecationWarning introduced in setuptools>=77

[peterdsharpe]

PhysicsNeMo Pull Request

Description

When installing PhysicsNeMo from source with setuptools>=77 (current latest release is v78), the following deprecation warning is emitted during install, from PhysicsNeMo:

      SetuptoolsDeprecationWarning: `project.license` as a TOML table is deprecated
      !!

              ********************************************************************************
              Please use a simple string containing a SPDX expression for `project.license`. You can also
      use `project.license-files`. (Both options available on setuptools>=77.0.0).

              By 2026-Feb-18, you need to update your project and remove deprecated calls
              or your builds will no longer be supported.

              See https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#license for
      details.
              ********************************************************************************

      !!

This originates from pyproject.toml, which previously contained:

license = {text = "Apache 2.0"}

and should now be the following SPDX-compatible identifier:

license = "Apache-2.0"

Related:

• PEP 639
• https://packaging.python.org/en/latest/guides/licensing-examples-and-user-scenarios/
• [Docs] Need migration guide for license expression (PEP 639) about TOML-table-based project.license deprecation if v77 unavailable  pypa/setuptools#4903

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• [N/A] The CHANGELOG.md is up to date with these changes.
• An issue is linked to this pull request.

Dependencies

[peterdsharpe]

/blossom-ci

[Copilot]

Copilot reviewed 1 out of 1 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

pyproject.toml:30

• The license classifier was removed; please verify that this change is intentional to ensure that package metadata remains correct for indexing on PyPI.

"License :: OSI Approved :: Apache Software License",

[ktangsali]

LGTM! Thank you for the detailed description section :)