ci: Windows / Py3.9: enable legacy "load DLLs from path" behavior

Keeping in sync with changes to #4590

Signed-off-by: Zach Lewis <[email protected]>

Author: zachlewis

.github/workflows/ci.yml

@@ -594,3 +594,4 @@ jobs:
             vsver: 2022
             generator: "Visual Studio 17 2022"
             python_ver: "3.9"
+            setenvs: export OIIO_PYTHON_LOAD_DLLS_FROM_PATH=1