Fix preset tracking setttings missing a comma

Preset tracking settings is missing a comma here.
Without a comma this will result in an implicit string concatenation.
This was probably not wanted.

Reviewed By: sergey, Blendify

Differential Revision: https://developer.blender.org/D6717

release/scripts/startup/bl_operators/presets.py

@@ -501,7 +501,7 @@ class AddPresetTrackingSettings(AddPresetBase, Operator):
         "settings.use_default_mask",
         "settings.use_default_red_channel",
         "settings.use_default_green_channel",
-        "settings.use_default_blue_channel"
+        "settings.use_default_blue_channel",
         "settings.default_weight"
     ]