Logger: union keys across the window instead of sampling from index 0 (#205)

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Co-authored-by: ClemensSchwarke <clemens.schwarke@gmail.com>

Author: kevinzakka

rsl_rl/utils/logger.py

@@ -158,7 +158,7 @@ def log(
             extras_string = ""
             if self.ep_extras:
                 # Iterate over all keys in the episode info dictionary
-                for key in self.ep_extras[0]:
+                for key in {k for ep_info in self.ep_extras for k in ep_info}:
                     infotensor = torch.tensor([], device=self.device)
                     # Iterate over all steps
                     for ep_info in self.ep_extras: