Bump ruff from 0.15.20 to 0.15.21

---
updated-dependencies:
- dependency-name: ruff
  dependency-version: 0.15.21
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

pyproject.toml

@@ -28,7 +28,7 @@ build-backend = "hatchling.build"
 path = "src/netbox_initializers/version.py"
 
 [dependency-groups]
-dev = ["ruff==0.15.20"]
+dev = ["ruff==0.15.21"]
 
 [tool.ruff]
 line-length = 100