chore(deps): Update ruff requirement in /spiffe in the dev-tools group

Updates the requirements on [ruff](https://github.com/astral-sh/ruff) to permit the latest version.

Updates `ruff` to 0.15.1
- [Release notes](https://github.com/astral-sh/ruff/releases)
- [Changelog](https://github.com/astral-sh/ruff/blob/main/CHANGELOG.md)
- [Commits](astral-sh/ruff@0.13.0...0.15.1)

---
updated-dependencies:
- dependency-name: ruff
  dependency-version: 0.15.1
  dependency-type: direct:development
  dependency-group: dev-tools
...

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

Author: dependabot[bot]

spiffe/pyproject.toml

@@ -21,7 +21,7 @@ Repository = "https://github.com/HewlettPackard/py-spiffe"
 
 [dependency-groups]
 dev = [
-  "ruff>=0.13,<0.14",
+  "ruff>=0.13,<0.16",
   "mypy>=1.19,<2",
   "pyright>=1.1.406,<2",
   "grpcio-tools>=1.76.0,<2",