build(deps): bump ruff from 0.15.4 to 0.15.6 in /pydantic-ai (#37)

Bumps [ruff](https://github.com/astral-sh/ruff) from 0.15.4 to 0.15.6.
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.15.4...0.15.6)

---
updated-dependencies:
- dependency-name: ruff
  dependency-version: 0.15.6
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pydantic-ai/pyproject.toml

@@ -13,7 +13,7 @@ dependencies = [
 [project.optional-dependencies]
 dev = [
     "pytest",
-    "ruff==0.15.4",
+    "ruff==0.15.6",
 ]
 
 [tool.setuptools.packages.find]

pydantic-ai/requirements.txt

@@ -5,4 +5,4 @@ pydantic-ai[openai]
 python-dotenv==1.2.2
 
 pytest
-ruff==0.15.5
+ruff==0.15.6