Bump ruff from 0.15.8 to 0.15.12 in the pip group

Bumps the pip group with 1 update: [ruff](https://github.com/astral-sh/ruff).


Updates `ruff` from 0.15.8 to 0.15.12
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.15.8...0.15.12)

---
updated-dependencies:
- dependency-name: ruff
  dependency-version: 0.15.12
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: pip
...

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

Author: dependabot[bot]

pyproject.toml

@@ -33,7 +33,7 @@ prometheus-xmpp-alerts = "prometheus_xmpp.__main__:main"
 
 [project.optional-dependencies]
 testing = ["pytz"]
-dev = ["ruff==0.15.8"]
+dev = ["ruff==0.15.12"]
 
 [tool.setuptools]
 packages = ["prometheus_xmpp"]