Fix a pyright error and bump the pyright action to v3

Author: gaborfeher

.github/workflows/linter.yaml

@@ -45,7 +45,7 @@ jobs:
       - name: Run Pyright (Pylance equivalent)
         id: pyright
         continue-on-error: true
-        uses: jakebailey/pyright-action@v2
+        uses: jakebailey/pyright-action@v3
         with:
           pylance-version: latest-release
 

src/a2a/contrib/tasks/vertex_task_store.py

@@ -32,7 +32,7 @@ class VertexTaskStore(TaskStore):
 
     def __init__(
         self,
-        client: 'vertexai.Client',  # type: ignore
+        client: vertexai.Client,  # type: ignore
         agent_engine_resource_id: str,
     ) -> None:
         """Initializes the VertexTaskStore.