CI: Windows artifacts no longer shipped

!4235 (merged) seems to have busted the Windows artifact shipping in some new and interesting way. The deployment job now reports:

Traceback (most recent call last):
  File "/builds/graphviz/graphviz/ci/deploy.py", line 280, in <module>
    sys.exit(main())
             ^^^^^^
  File "/builds/graphviz/graphviz/ci/deploy.py", line 242, in main
    assert len(webdata["windows"]) > 0, "no Windows artifacts found"
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: no Windows artifacts found