Remove forced mujoco version from tests

.github/workflows/test.yml

@@ -8,7 +8,7 @@ on:
 
 jobs:
   linux-test:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     strategy:
       matrix:
         python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
@@ -21,7 +21,6 @@ jobs:
     - name: Install dependencies
       run: |
         pip install pytest
-        pip install mujoco==2.3.2
         git clone https://github.com/benelot/pybullet-gym.git
         pip install -e pybullet-gym
         sudo apt-get update