In #3803, we changed the license field like this:

-license = "Apache-2.0"
+license = {text = "Apache-2.0"}

But license field spec was updated in May 2024. Now license is SPDX license expression.
So we should use license = "Apache-2.0" again.

https://packaging.python.org/en/latest/specifications/pyproject-toml/#license

Additionally, using License :: classifiers is now deprecated.

https://packaging.python.org/en/latest/specifications/pyproject-toml/#classifiers