libs/unit/adc_v11.py: Fix get_voltage missing parenthesis.

Signed-off-by: Pedro Marquez <[email protected]>

Author: pmmarquez

m5stack/libs/unit/adc_v11.py

@@ -27,7 +27,7 @@ def _available(self):
             raise UnitError("ADC V1.1 Unit not found in Grove")
 
     def get_voltage(self):
-        data = self.get_adc_raw_value
+        data = self.get_adc_raw_value()
         vol = (
             data
             * 2.048