Fix reflection probe image assignment in Blender 4.2

Blender 4.2 no longer allows images (or possibly anything) to be assigned to uninitialized Group IDProperties via key access, e.g. `probe_component['envMapTexture'] = img` isn't allowed anymore.
Images are now assigned directly to the property without going through the key, e.g. `probe_component.envMapTexture = img`.
Note: `setattr` also works because it also directly assigns without going through the key.

addons/io_hubs_addon/components/definitions/reflection_probe.py

@@ -294,7 +294,7 @@ def modal(self, context, event):
                         else:
                             update_image_editors(old_img, img)
 
-                    probe_component['envMapTexture'] = img
+                    probe_component.envMapTexture = img
 
                     # Pack image and update filepaths so that it displays/unpacks nicely for the user.
                     # Note: updating the filepaths prints an error to the terminal, but otherwise seems to work fine.
@@ -449,11 +449,11 @@ def execute(self, context):
             for probe in probes:
                 if f.name.startswith(f"{probe.name} - EnvMap"):
                     probe_component = probe.hubs_component_reflection_probe
-                    old_img = probe_component['envMapTexture']
+                    old_img = probe_component.envMapTexture
 
                     img = bpy.data.images.load(
                         filepath=os.path.join(dirname, f.name))
-                    probe_component['envMapTexture'] = img
+                    probe_component.envMapTexture = img
 
                     if old_img:
                         if self.overwrite_images: