Fix Ruff failures (#5083)

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "detection_rules"
-version = "1.3.32"
+version = "1.3.33"
 description = "Detection Rules is the home for rules used by Elastic Security. This repository is used for the development, maintenance, testing, validation, and release of rules for Elastic Security’s Detection Engine."
 readme = "README.md"
 requires-python = ">=3.12"

tests/test_all_rules.py

@@ -1293,7 +1293,7 @@ class TestBuildTimeFields(BaseRuleTest):
 
             errors = []
             for build_field, field_versions in build_fields.items():
-                start_ver, end_ver = field_versions
+                start_ver, _ = field_versions
                 # when a _new_ build time field is introduced, _all_ rules _must_ have a min_stack_version for the stack
                 # version in which the field was introduced. This is because the initial change will result in a hash
                 # change which is different because of the build time fields.