Add `agent.pt` and tag the environment

This commit adds a model that is compatible with the 🥇 [Open RL Leaderboard](https://huggingface.co/spaces/open-rl-leaderboard/leaderboard) 🥇.

README.md

@@ -5,6 +5,7 @@ tags:
 - deep-reinforcement-learning
 - reinforcement-learning
 - stable-baselines3
+- Swimmer-v4
 model-index:
 - name: TRPO
   results:

agent.pt

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:56eb5f9b98b221863fb6992d1bc03f3974c68c01aaa7512273f4f8639f41f5b3
-size 24230
+oid sha256:3cd0c4a442ba5f112829d2422fb92703a90e2c8f160ed4e135a74e84367eecc1
+size 25354