[Fix] log WandB scalars using correct step argument

Author: Ibinarriaga8

torchrl/record/loggers/wandb.py

@@ -234,6 +234,6 @@ def log_str(self, name: str, value: str, step: int | None = None) -> None:
         table = wandb.Table(columns=["text"], data=[[value]])
 
         if step is not None:
-            self.experiment.log({name: table, "trainer/step": step})
+            self.experiment.log({name: value}, step=step)
         else:
             self.experiment.log({name: table})