feat: add Bollinger Bands factor

Author: Satvik-Singh192

tests/test_factors.py

@@ -3,15 +3,15 @@
 import numpy as np
 import pandas as pd
 import pytest
-
-from quant_research_starters.factors import (
+from quant_research_starter.factors import (
     BollingerBandsFactor,
     MomentumFactor,
     SizeFactor,
     ValueFactor,
     VolatilityFactor,
 )
 
+
 @pytest.fixture
 def sample_prices():
     """Create sample price data for testing."""