Fix: Sculpt performance test doesn't run

Incomplete fix in ed91a298c0

`StrEnum` is also a concept that doesn't exist in python 3.9

Pull Request: https://projects.blender.org/blender/blender/pulls/137624

tests/performance/tests/sculpt.py

@@ -13,7 +13,7 @@ class SculptMode(enum.IntEnum):
     DYNTOPO = 3
 
 
-class BrushType(enum.StrEnum):
+class BrushType(enum.Enum):
     DRAW = "Draw"
     CLAY_STRIPS = "Clay Strips"
     SMOOTH = "Smooth"
@@ -99,7 +99,7 @@ def prepare_sculpt_scene(context: any, mode: SculptMode, brush_type: BrushType):
     bpy.ops.brush.asset_activate(
         asset_library_type='ESSENTIALS',
         relative_asset_identifier='brushes/essentials_brushes-mesh_sculpt.blend/Brush/' +
-        brush_type)
+        brush_type.value)
 
     # Reduce the brush strength to avoid deforming the mesh too much and influencing multiple strokes
     context.tool_settings.sculpt.brush.strength = 0.1