[agentic-rag-toolbox-cloudsql] Update default python version for uv init

[gitsnead]

Not sure if this is an issue with the Cloud Shell environment or a step that I missed in the codelab. You can see the state of my Cloud Shell environment when encountered the issue below.

$ update-alternatives --list python
update-alternatives: error: no alternatives for python
$ python --version
Python 3.12.3

When I start out with an empty directory and run uv init, it sets 3.12 in the .python-version file.

This works fine for the lab when running everything local on Cloud Shell. However, the build fails when I attempt to deploy the restaurant_agent service to Cloud Run with this command:

gcloud run deploy restaurant-agent \
  --source . \
  --region $REGION \
  --set-env-vars "TOOLBOX_URL=$TOOLBOX_URL,GOOGLE_CLOUD_PROJECT=$GOOGLE_CLOUD_PROJECT,GOOGLE_CLOUD_LOCATION=$GOOGLE_CLOUD_LOCATION,GOOGLE_GENAI_USE_VERTEXAI=TRUE" \
  --allow-unauthenticated \
  --quiet

I found this in Cloud Build log for that run:

Using Python version from /workspace/.python-version: 3.12
--
  | Failed to resolve version 3.12 for Python from region us-central1: failed to resolve version matching: 3.12 against [3.14.5 3.14.4 3.14.3 3.14.2 3.14.1 3.14.0 3.13.13 3.13.12 3.13.11 3.13.10 3.13.9 3.13.8 3.13.7 3.13.6 3.13.5 3.13.4 3.13.3 3.13.2 3.13.1 3.13.0]
  | Failed to resolve version 3.12 for Python from region us: failed to resolve version matching: 3.12 against [3.14.5 3.14.4 3.14.3 3.14.2 3.14.1 3.14.0 3.13.13 3.13.12 3.13.11 3.13.10 3.13.9 3.13.8 3.13.7 3.13.6 3.13.5 3.13.4 3.13.3 3.13.2 3.13.1 3.13.0]
  | --------------------------------------------------------------------------------
  | failed to build: (error ID: 1ff870e4):
  | invalid Python version specified: failed to resolve version matching: 3.12 against [3.14.5 3.14.4 3.14.3 3.14.2 3.14.1 3.14.0 3.13.13 3.13.12 3.13.11 3.13.10 3.13.9 3.13.8 3.13.7 3.13.6 3.13.5 3.13.4 3.13.3 3.13.2 3.13.1 3.13.0] . Version constraint "3.12" not satisfied by any available versions in Artifact Registry. You may need to use a different builder. Please check if the language version specified is supported. You can refer to https://cloud.google.com/docs/buildpacks/builders for a list of compatible runtime languages per builder
  | --------------------------------------------------------------------------------
  | Sorry your project couldn't be built.

I used these commands to upgrade the project to Python 3.14 which the docs said is a supported version for Cloud Build.

uv python upgrade 3.14
uv python update-shell

After restarting my shell as recommended, I was able to run all the local tests and build restaurant_agent after matching the python version in my Cloud Shell instance to the expected one for Cloud Build.