Fix T99036: hex color in "Add Color Attribute"

Proposed solution by @scurest The color attribute in the RNA was tagged as
 COLOR_GAMMA. This change will change it to a regular COLOR.

{F13217692}

Reviewed By: joeedh, jbakker

Maniphest Tasks: T99036

Differential Revision: https://developer.blender.org/D15272

source/blender/editors/geometry/geometry_attributes.cc

@@ -405,7 +405,7 @@ void GEOMETRY_OT_color_attribute_add(wmOperatorType *ot)
 
   prop = RNA_def_float_color(
       ot->srna, "color", 4, nullptr, 0.0f, FLT_MAX, "Color", "Default fill color", 0.0f, 1.0f);
-  RNA_def_property_subtype(prop, PROP_COLOR_GAMMA);
+  RNA_def_property_subtype(prop, PROP_COLOR);
   RNA_def_property_float_array_default(prop, default_color);
 }