Fixes problems raised by Ruff Linter

Specifically, this fixes Q000, F821 and F541 identified previously on
lines 126, 128 and 130

Author: shodanwashere

dojo/tools/checkov/parser.py

@@ -121,13 +121,14 @@ def get_item(vuln, test, check_type):
 
     if "description" in vuln:
         description += f"\n{vuln['description']}\n"
-
+    
+    mitigation = ""
     if "benchmarks" in vuln:
-        bms = vuln['benchmarks'].keys()
+        bms = vuln["benchmarks"].keys()
         if len(bms) > 0:
-            mitigation += f"\nBenchmarks:\n"
+            mitigation += "\nBenchmarks:\n"
             for bm in bms:
-                for gl in vuln['benchmarks'][bm]:
+                for gl in vuln["benchmarks"][bm]:
                     mitigation += f"- {bm} # {gl['name']} : {gl['description']}\n"
 
     file_path = vuln.get("file_path", None)