add nanopb bazel dep to bazel workspace check

tools/run_tests/sanity/check_bazel_workspace.py

@@ -47,6 +47,7 @@ _GRPC_DEP_NAMES = [
     'com_google_protobuf',
     'com_github_google_googletest',
     'com_github_gflags_gflags',
+    'com_github_nanopb_nanopb',
     'com_github_google_benchmark',
     'com_github_cares_cares',
     'com_google_absl',