fix: PrivateEndpoint.raw_predict parameter name

Fixes #6101

Changed parameter name from 'body' to 'data' in PrivateEndpoint.raw_predict
to match google-auth-transport's AuthorizedSession.post() API signature.

The google-auth-transport library updated its API, changing the parameter
name from 'body' to 'data'. The Endpoint class was already updated to use
'data', but PrivateEndpoint class was missed, causing TypeError when calling
raw_predict() on PrivateEndpoint instances.

This fix aligns PrivateEndpoint.raw_predict() with Endpoint.raw_predict()
implementation.

Signed-off-by: Yashwant Bezawada <yashwant_b@me.com>

Author: yashwantbezawada

google/cloud/aiplatform/models.py

@@ -4150,7 +4150,7 @@ def raw_predict(
             url = f"https://{endpoint_override}/v1/projects/{self.project}/locations/{self.location}/endpoints/{self.name}:rawPredict"
             return self._authorized_session.post(
                 url=url,
-                body=body,
+                data=body,
                 headers=headers,
             )