Disable OSG_USE_UTF8_FILENAME

To match vcpkg openmw-osg port.

Author: elsid

.github/workflows/build.yaml

@@ -64,7 +64,6 @@ jobs:
         -D OSG_MSVC_VERSIONED_DLL=OFF
         -D OSG_DETERMINE_WIN_VERSION=OFF
         -D OSG_FIND_3RD_PARTY_DEPS=OFF
-        -D OSG_USE_UTF8_FILENAME=ON
         -D BUILD_OSG_PLUGINS_BY_DEFAULT=OFF
         -D BUILD_OSG_PLUGIN_OSG=ON
         -D BUILD_OSG_PLUGIN_DDS=ON