[RLlib][fix] Fixed a small bug in type hints of the 'learner_connector'. (#57673)

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## Why are these changes needed?

The type hints for `learner_connector` in `AlgorithmConfig.training` was
deprecated still using the `RLModule` as parameter. This PR adjust type
hints to the actual expected form of the callable.

## Related issue number

<!-- For example: "Closes #1234" -->

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Signed-off-by: simonsays1980 <[email protected]>

Author: simonsays1980

rllib/algorithms/algorithm_config.py

@@ -2354,7 +2354,10 @@ def training(
         # Moved to `learners()` method.
         learner_class: Optional[Type["Learner"]] = NotProvided,
         learner_connector: Optional[
-            Callable[["RLModule"], Union["ConnectorV2", List["ConnectorV2"]]]
+            Callable[
+                [gym.spaces.Space, gym.spaces.Space],
+                Union["ConnectorV2", List["ConnectorV2"]],
+            ]
         ] = NotProvided,
         add_default_connectors_to_learner_pipeline: Optional[bool] = NotProvided,
         learner_config_dict: Optional[Dict[str, Any]] = NotProvided,