fix(safety): remove unused git sub token (flake8 F841)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: Violet2314

trpc_agent_sdk/safety/_rules.py

@@ -706,7 +706,6 @@ def _check_bash(self, scan_input: ScanInput, policy: PolicyConfig) -> list[Safet
             for i, tok in enumerate(tokens):
                 base = tok.split("/")[-1].lower()
                 if base == "git" and i + 1 < len(tokens):
-                    sub = tokens[i + 1].lstrip("-").lower()
                     # skip global flags like -C / --git-dir between git and subcmd
                     j = i + 1
                     while j < len(tokens) and tokens[j].startswith("-"):