Pose library: remove unused parameter

Remove an unused `context` parameter from
`pose_library.pose_creation.create_pose_asset()`. Normally this wouldn't
make it into the release branch, but this particular function could be
the basis for custom pose library creation code, and thus it's good if
it has a nicer API in the release.

No functional changes.

pose_library/pose_creation.py

@@ -302,7 +302,6 @@ class PoseActionCreator:
 
 
 def create_pose_asset(
-    context: Context,
     params: PoseCreationParams,
 ) -> Optional[Action]:
     """Create a single-frame Action containing only the pose of the given bones.
@@ -334,7 +333,7 @@ def create_pose_asset_from_context(context: Context, new_asset_name: str) -> Opt
         new_asset_name,
     )
 
-    return create_pose_asset(context, params)
+    return create_pose_asset(params)
 
 
 def copy_fcurves(