message: Fix `workspace_status_command` on Windows
diff: # Enable support for absl types like string_view in gtest.
  build --define="absl=1"
  -run --define="absl=1"
  -test --define="absl=1"
  -# Cannot use 'common' because 'bazel version' fails with this.
  # Gather build version information
  -build --workspace_status_command=bazel/build-version.py
  -run --workspace_status_command=bazel/build-version.py
  -test --workspace_status_command=bazel/build-version.py
  +build:linux --workspace_status_command=bazel/build-version.py
  +build:macos --workspace_status_command=bazel/build-version.py
  +build:windows --workspace_status_command="python bazel/build-version.py"
  build --enable_platform_specific_config
  