message: Remove pdb and other unneeded files from Windows build directory
  This PR remove pdb and other unneeded files from Windows build directory,
  so that it is possible to upload the artifact to GitHub Actions
  (seems the previous failure was caused by artifact too large).
diff: @@ -341,9 +341,10 @@ jobs:
  cat .bazelrc
  bazel build -s %BAZEL_OPTIMIZATION% //tensorflow_io:python/ops/libtensorflow_io.so //tensorflow_io:python/ops/libtensorflow_io_plugins.so //tensorflow_io_gcs_filesystem/...
  if %errorlevel% neq 0 exit /b %errorlevel%
  - mkdir build
  + mkdir -p build
  cp -r bazel-bin/tensorflow_io build
  cp -r bazel-bin/tensorflow_io_gcs_filesystem build
  + bash -c "find build -not -name '*.so' -type f | xargs rm -rf"
  - uses: actions/upload-artifact@v2
  with:
  name: ${{ runner.os }}-bazel-bin
  