The holiday is declared by the government, not by an individual. It's a person's own decision whether or not to vote. There is no provision to take any action against the individual for this.
Individual Choices and Holidays
What if a person doesn't fire crackers on Diwali? What if a person doesn't fly kites on Kite Flying Day? It's the choice of the individual.
Encouraging Voting Among Employees
Have you educated your employees to vote or encouraged them? Many Ahmedabad-based pharma companies have started practices to encourage voting on the 23rd in Gujarat.
Rather than punishing, it's better to focus on other aspects of your employees.