Fix rgba value in oven_asset.xml to be in [0,1]

The mujoco xml docs state that "All [rgba] components should be in the
range [0 1]."
https://mujoco.readthedocs.io/en/stable/XMLreference.html#asset-material

MuJoCo's parser clearly let's this through. But it seems that mine is
a little more strict.

I checked with the original author @abhishekunique, and he confirmed
that it's just a bug (from his original work), and that it should be
fixed.

gymnasium_robotics/envs/assets/kitchen_franka/kitchen_assets/item_assets/oven_asset.xml

@@ -20,7 +20,7 @@
         <material name="oven_wood" texture="T_oven_wood" texrepeat="3 3" reflectance="0.7" shininess=".4" texuniform="false"/>
         <material name="oven_metal" rgba="1 1 1 1" texture="T_oven_metal" texrepeat="3 3" reflectance="1" shininess="1" texuniform="false"/>
         <material name="oven_black" rgba=".15 .15 .15 1" reflectance=".2" shininess=".2" />
-        <material name="oven_burner" rgba="2 0 0 1" reflectance=".2" shininess=".2" />
+        <material name="oven_burner" rgba="1 0 0 1" reflectance=".2" shininess=".2" />
         <material name="oven_block" rgba=".1 .1 .1 1"/>
         <material name="oven_collision_blue" rgba="0.3 0.3 1.0 0.5" shininess="0" specular="0"/>
     </asset>