chore(deps-dev): bump ruff in /tools/tokenserver/loadtests

Bumps [ruff](https://github.com/astral-sh/ruff) from 0.12.12 to 0.15.5.
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.12.12...0.15.5)

---
updated-dependencies:
- dependency-name: ruff
  dependency-version: 0.15.5
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

tools/tokenserver/loadtests/poetry.lock

@@ -23,7 +23,7 @@ sqlalchemy = "1.4.46"
 [tool.poetry.group.dev.dependencies]
 mypy = "^1.19.1"
 pydocstyle = "^6.3.0"
-ruff = "^0.15.6"
+ruff = "^0.15.7"
 black = "^26.3.1"
 bandit = "^1.9.4"
 isort = "^8.0.1"