Recent changes to path handling (most likely [0]) caused
AssetCatalogTest.create_catalog_after_loading_file to fail on WIN32.
The test relied on the resulting path to be joined with "/" as a path
separator. The resulting path used both forward and back-slashes.
While these do work for some API's on WIN32, mixing both in a file path
isn't expected behavior in most cases, so update the tests to use native
slash direction for file-paths.
[0]: 9f6a045e23
e96ad822b3