Minor type hint improvments

[igalshilman]

No description provided.

[Copilot]

Pull Request Overview

This PR introduces minor type hint improvements to enhance the precision of generic types across promise-related and awaitable functions.

• Updated function signatures in server_context.py and context.py to include an optional "type_hint" parameter while refining return type annotations.
• Adjusted example code in workflow.py and virtual_object.py to pass explicit type hints where applicable.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
python/restate/server_context.py	Updated promise signature with type_hint parameter and added await method implementation.
python/restate/context.py	Revised return type annotations and added type_hint parameter to functions.
examples/workflow.py	Passed explicit type hint in the promise call.
examples/virtual_object.py	Passed explicit type hint to get method for retrieving counter value.