Merge pull request #6491 from soltanmm/license-to-nil

Add explicit license to grpcio-tools setup.py
diff --git a/tools/distrib/python/grpcio_tools/setup.py b/tools/distrib/python/grpcio_tools/setup.py
index 4cc1a1e..576f7ae 100644
--- a/tools/distrib/python/grpcio_tools/setup.py
+++ b/tools/distrib/python/grpcio_tools/setup.py
@@ -83,7 +83,7 @@
 setuptools.setup(
   name='grpcio_tools',
   version=grpc_version.VERSION,
-  license='',
+  license='3-clause BSD',
   ext_modules=maybe_cythonize([
       protoc_ext_module(),
   ]),