Update distributed_tuning.ipynb (#355)

Add pip install tf-text; otherwise it errors out when loading Gemma

site/en/gemma/docs/distributed_tuning.ipynb

@@ -204,7 +204,7 @@
         "# Work around an import error with tensorflow-hub. The library is not used.\n",
         "!pip install -q -U tensorflow-hub\n",
         "# Install tensorflow-cpu so tensorflow does not attempt to access the TPU.\n",
-        "!pip install -q -U tensorflow-cpu\n",
+        "!pip install -q -U tensorflow-cpu tensorflow-text\n",
         "# Install keras 3 last. See https://keras.io/getting_started for details.\n",
         "!pip install -q -U keras"
       ]