Fix mjSpec colab after changing the default behavior of attach to be a shallow copy.

PiperOrigin-RevId: 724375710
Change-Id: I5fac7d24c1d0b1ad4d427c021022c47620accf53

python/mjspec.ipynb

@@ -368,6 +368,7 @@
     "  \"\"\"Constructs a creature with `num_legs` legs.\"\"\"\n",
     "  rgba = random_state.uniform([0, 0, 0, 1], [1, 1, 1, 1])\n",
     "  spec = mj.MjSpec.from_string(creature_model)\n",
+    "  spec.copy_during_attach = True\n",
     "\n",
     "  # Attach legs to equidistant sites on the circumference.\n",
     "  spec.worldbody.first_geom().rgba = rgba\n",
@@ -672,6 +673,7 @@
     "#@title Humanoid with arms replaced by legs.{vertical-output: true}\n",
     "\n",
     "spec = mj.MjSpec.from_file(humanoid_file)\n",
+    "spec.copy_during_attach = True\n",
     "\n",
     "# Get the torso, arm, and leg bodies\n",
     "arm_left = spec.find_body('upper_arm_left')\n",
@@ -781,6 +783,7 @@
     "\n",
     "humanoid = mj.MjSpec.from_file(humanoid_file)\n",
     "spec = mj.MjSpec()\n",
+    "spec.copy_during_attach = True\n",
     "\n",
     "# Delete all key frames to avoid name conflicts\n",
     "while humanoid.keys:\n",