Fix license deprecation warning (#2511)

Table-based license keys of the form `license = {text =
"<license-string>"}` are deprecated since `setuptools >= 77.0.0` and
produces warning:
> SetuptoolsDeprecationWarning: `project.license` as a TOML table is
deprecated

This PR aligns with new format of license expression ([PEP
639](https://peps.python.org/pep-0639/#add-license-expression-field)).

Author: antonwolfy

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * `--onemkl-interfaces` and `--onemkl-interfaces-dir` options for building script are deprecated, instead `--onemath` and `--onemath-dir` are introduced to be aligned with [oneMath specification](https://oneapi-spec.uxlfoundation.org/specifications/oneapi/latest/elements/onemath/source/) [#2487](https://github.com/IntelPython/dpnp/pull/2487)
 * Clarified description of `xp` keyword in docstring of `dpnp.interp` [#2506](https://github.com/IntelPython/dpnp/pull/2506)
 * Updated existing GitHub workflows to add testing with Python 3.13 [#2510](https://github.com/IntelPython/dpnp/pull/2510)
+* Aligned the license expression with `PEP-639` [#2511](https://github.com/IntelPython/dpnp/pull/2511)
 
 ### Deprecated
 

pyproject.toml

@@ -66,7 +66,8 @@ keywords = [
   "gpu",
   "dpcpp"
 ]
-license = {text = "Apache 2.0"}
+license = "BSD-2-Clause"
+license-files = ["LICENSE.txt"]
 maintainers = [{name = "Intel Corporation"}]
 name = "dpnp"
 readme = {file = "README.md", content-type = "text/markdown"}