Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: zliang-akamai

test/unit/fixtures.py

@@ -33,7 +33,7 @@ def _load_fixtures(self):
             if json_file.suffix != ".json":
                 continue
 
-            with open(FIXTURES_DIR / json_file) as f:
+            with open(json_file) as f:
                 raw = f.read()
 
             data = json.loads(raw)