fix: apply black formatting to vectorized.py

- Fix code formatting to pass CI/CD black check

- All tests still pass after formatting

Author: saumya1317

src/quant_research_starter/backtest/__pycache__/vectorized.cpython-313.pyc

@@ -94,7 +94,7 @@ def run(self, weight_scheme: str = "rank") -> Dict:
         rebalance_mask_df = pd.DataFrame(
             np.tile(rebalance_mask.values.reshape(-1, 1), (1, len(weights.columns))),
             index=weights.index,
-            columns=weights.columns
+            columns=weights.columns,
         )
         weights = weights.where(rebalance_mask_df, weights.shift(1).fillna(0.0))