fix: resolve linter errors in Android modules

- Remove unused imports from mobsf_scanner.py (asyncio, hashlib, json, Optional)
- Remove unused variables from opengrep_android.py (start_col, end_col)
- Remove duplicate Path import from workflow.py

backend/toolbox/modules/android/mobsf_scanner.py

@@ -16,14 +16,11 @@ Performs static analysis on APK files including permissions, manifest analysis,
 #
 # Additional attribution and requirements are provided in the NOTICE file.
 
-import asyncio
-import hashlib
-import json
 import logging
 import os
 from collections import Counter
 from pathlib import Path
-from typing import Dict, Any, List, Optional
+from typing import Dict, Any, List
 import aiohttp
 
 try: