feat(renovate): add renovate configuration for auto-updating toolbox version in build file of Python SDK

[SaxenaAnushka102]

Description

This PR adds the official Renovate configuration (renovate.json) to the Python SDK repository.

This configuration enables automated dependency tracking for the upstream Toolbox server:

• What it does: Uses the regexManagers to watch the googleapis/genai-toolbox releases.
• Action: This Renovate configuration uses a regexManagers block with-

• "datasourceTemplate": "github-releases"
• "depNameTemplate": "googleapis/genai-toolbox"

This tells Renovate to:

Look for new versions of the dependency by checking the GitHub Releases of the repository specified in depNameTemplate.
In this case, Renovate polls or checks for new releases/tags on https://github.com/googleapis/genai-toolbox.
The matchStrings regex extracts the current version from integration.cloudbuild.yaml. Renovate then compares this to the versions available via GitHub releases for googleapis/genai-toolbox.

• Maintenance: This eliminates the need for manual version checks and updating.

Local test results

python-renovate-logs.txt

{
             "description": "Auto-update genai-toolbox server version",
             "matchPackageNames": ["googleapis/genai-toolbox"],
             "matchManagers": ["custom.regex"],
             "branchName": "auto-update/toolbox-server-v{{newValue}}",
             "commitMessageTopic": "chore(deps): update genai-toolbox server to {{newValue}}",
             "groupName": false,
             "matchUpdateTypes": ["minor", "patch"]
           },
DEBUG: 4 flattened updates found: llama-index, googleapis/genai-toolbox, googleapis/genai-toolbox, googleapis/genai-toolbox (repository=SaxenaAnushka102/mcp-toolbox-sdk-python)
{
             "deps": [
               {
                 "depName": "googleapis/genai-toolbox",
                 "packageName": "googleapis/genai-toolbox",
                 "currentValue": "0.12.0",
                 "datasource": "github-releases",
                 "versioning": "semver",
                 "replaceString": "_TOOLBOX_VERSION: '0.12.0'",
                 "updates": [
                   {
                     "bucket": "non-major",
                     "newVersion": "v0.15.0",
                     "newValue": "0.15.0",
                     "releaseTimestamp": "2025-09-19T00:31:11.000Z",
                     "newVersionAgeInDays": 6,
                     "newMajor": 0,
                     "newMinor": 15,
                     "newPatch": 0,
                     "updateType": "minor",
                     "isBreaking": true,
                     "libYears": 0.09598468417047185,
                     "branchName": "auto-update/toolbox-server-v0.15.0"
                   }
                 ],
                 "warnings": [],
                 "sourceUrl": "https://github.com/googleapis/genai-toolbox",
                 "registryUrl": "https://github.com",
                 "mostRecentTimestamp": "2025-09-19T00:31:11.000Z",
                 "currentVersion": "v0.12.0",
                 "currentVersionTimestamp": "2025-08-14T23:41:38.000Z",
                 "currentVersionAgeInDays": 41,
                 "isSingleVersion": true,
                 "fixedVersion": "0.12.0"
               }
             ]
DEBUG: findPr(auto-update/toolbox-server-v0.15.0, chore(deps): update chore(deps): update genai-toolbox server to 0.15.0 to v0.15.0, !open) (repository=SaxenaAnushka102/mcp-toolbox-sdk-python, branch=auto-update/toolbox-server-v0.15.0)

Relates issues

Resolves #379

[anubhav756]

nit: Also, the PR description seems to talk about the "Go SDK repository". Should this be Python SDK repository for now?

[SaxenaAnushka102]

nit: Also, the PR description seems to talk about the "Go SDK repository". Should this be Python SDK repository for now?

Sorry for the confusion, I've changed it. Thanks!