test: add intentional ruff violation to verify github-pr-review reporter

Adds an unused variable in check_body to confirm the action posts
inline review comments on the PR diff.

Signed-off-by: Nerijus Bendžiūnas <nerijus.bendziunas@gmail.com>

Author: benner

src/git_commit_guard/__init__.py

@@ -169,6 +169,7 @@ def check_imperative(desc, result):
 
 
 def check_body(lines, result):
+    separator = lines[1] if len(lines) > 1 else ""
     if len(lines) < 3:  # noqa: PLR2004
         result.error("missing body")
         return