Fix: keep Colab default torch, only install sympy fix + training libs

KernelX_Training.ipynb

@@ -45,7 +45,7 @@
    "execution_count": null,
    "metadata": {},
    "outputs": [],
-   "source": "!pip install -q \"sympy>=1.13,<1.14\" \"torch>=2.1,<2.5\" \"transformers==4.46.3\" \"trl==0.15.2\" \"peft>=0.13,<0.15\" datasets \"accelerate>=0.34,<0.36\" huggingface_hub\n\n# Restart runtime to pick up new torch/sympy versions\nimport os\nos.kill(os.getpid(), 9)"
+   "source": "!pip install -q \"sympy>=1.13,<1.14\" \"transformers==4.46.3\" \"trl==0.15.2\" \"peft>=0.13,<0.15\" datasets \"accelerate>=0.34,<0.36\" huggingface_hub\n\n# Restart runtime to pick up new sympy version (torch stays as Colab's default)\nimport os\nos.kill(os.getpid(), 9)"
   },
   {
    "cell_type": "markdown",