chore: fix license to correct spdx name

This is not a license change. This fixes the license value to the
correct spdx name per https://spdx.org/licenses/ to match the LICENSE
file.

Author: willkg

setup.py

@@ -45,7 +45,7 @@ def get_version():
     maintainer="Will Kahn-Greene",
     maintainer_email="willkg@mozilla.com",
     url="https://github.com/mozilla/bleach",
-    license="Apache Software License",
+    license="Apache License 2.0",
     license_files=["LICENSE", "bleach/_vendor/html5lib-1.1.dist-info/LICENSE"],
     packages=find_packages(),
     include_package_data=True,