chore(deps): bump google-genai from 2.3.0 to 2.6.0

Bumps [google-genai](https://github.com/googleapis/python-genai) from 2.3.0 to 2.6.0.
- [Release notes](https://github.com/googleapis/python-genai/releases)
- [Changelog](https://github.com/googleapis/python-genai/blob/main/CHANGELOG.md)
- [Commits](googleapis/python-genai@v2.3.0...v2.6.0)

---
updated-dependencies:
- dependency-name: google-genai
  dependency-version: 2.6.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

pyproject.toml

@@ -15,7 +15,7 @@ dependencies = [
     "anthropic>=0.102.0,<0.103",
     "babel>=2.17,<2.19",
     "fsspec>=2026.4.0,<2026.5",
-    "google-genai>=2.3.0,<2.4",
+    "google-genai>=2.6.0,<2.7",
     "httpx>=0.28.1,<0.29.0",
     "keyring>=25.7.0,<25.8",
     "markdown2>=2.5.4,<2.6",