Update deprecated license info in pyproject.toml (pvlib#2441)

* Update pyproject.toml

* Update v0.12.1.rst

Author: RDaxini

docs/sphinx/source/whatsnew/v0.12.1.rst

@@ -30,6 +30,8 @@ Testing
 
 Maintenance
 ~~~~~~~~~~~
+* Update ``pyproject.toml`` to replace deprecated license table and
+  classifiers. (:issue:`2440`, :pull:`2441`)
 
 
 Contributors

pyproject.toml

@@ -18,10 +18,9 @@ dependencies = [
     'scipy >= 1.6.0',
     'h5py',
 ]
-license = { text = "BSD-3-Clause" }
+license = "BSD-3-Clause"
 classifiers = [
     'Development Status :: 4 - Beta',
-    'License :: OSI Approved :: BSD License',
     'Operating System :: OS Independent',
     'Intended Audience :: Science/Research',
     'Programming Language :: Python',