Updates rsl_rl to 3.1.2 to support state-dependent std dev (#3867)

# Description

Updating rsl_rl to 3.1.2 release to support use these two changes in
IsaacLab sim-to-real deployed
[policies](https://github.com/isaac-sim/IsaacLab/tree/main/source/isaaclab_tasks/isaaclab_tasks/manager_based/manipulation/deploy).

Main commits of interest:

https://github.com/leggedrobotics/rsl_rl/commit/530f71aa71f182fd87fe0730313090459fded02d

https://github.com/leggedrobotics/rsl_rl/commit/a4d108a7bafd56b2aa50a3fba92ed6801b4eccaa

## Type of change
- New feature (non-breaking change which adds functionality)

- [x] I have read and understood the [contribution
guidelines](https://isaac-sim.github.io/IsaacLab/main/source/refs/contributing.html)
- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

---------
Signed-off-by: Ashwin Varghese Kuruttukulam <123109010+ashwinvkNV@users.noreply.github.com>
Signed-off-by: Kelly Guo <kellyg@nvidia.com>
Co-authored-by: Kelly Guo <kellyg@nvidia.com>

source/isaaclab_rl/setup.py

@@ -46,7 +46,7 @@ EXTRAS_REQUIRE = {
         "rl-games @ git+https://github.com/isaac-sim/rl_games.git@python3.11",
         "gym",
     ],  # rl-games still needs gym :(
-    "rsl-rl": ["rsl-rl-lib==3.0.1", "onnxscript>=0.5"],  # linux aarch 64 requires manual onnxscript installation
+    "rsl-rl": ["rsl-rl-lib==3.1.2", "onnxscript>=0.5"],  # linux aarch 64 requires manual onnxscript installation
 }
 # Add the names with hyphens as aliases for convenience
 EXTRAS_REQUIRE["rl_games"] = EXTRAS_REQUIRE["rl-games"]