[mypy] Add/fix type annotations for electronics algorithms (TheAlgorithms#4247)

* Fix mypy errors for scheduling/first_come_first_served

* Fix mypy errors for scheduling/round_robin.py

* Fix mypy errors for scheduling/shortest_job_first.py

* Fix isort errors

* Fix mypy errors for electronics/ohms_law.py

* Fix mypy errors for electronics/electric_power.py

* Fix black errors

Author: shan7030

electronics/electric_power.py

@@ -1,8 +1,9 @@
 # https://en.m.wikipedia.org/wiki/Electric_power
 from collections import namedtuple
+from typing import Tuple
 
 
-def electric_power(voltage: float, current: float, power: float) -> float:
+def electric_power(voltage: float, current: float, power: float) -> Tuple:
     """
     This function can calculate any one of the three (voltage, current, power),
     fundamental value of electrical system.

electronics/ohms_law.py

@@ -1,7 +1,8 @@
 # https://en.wikipedia.org/wiki/Ohm%27s_law
+from typing import Dict
 
 
-def ohms_law(voltage: float, current: float, resistance: float) -> float:
+def ohms_law(voltage: float, current: float, resistance: float) -> Dict[str, float]:
     """
     Apply Ohm's Law, on any two given electrical values, which can be voltage, current,
     and resistance, and then in a Python dict return name/value pair of the zero value.