Does my fasting become void if I lie out of fear of the consequences of telling the truth?

If you fear the oppression of your superior, it is better not to lie, for in allusions there is a way out of lying. Lying is permissible to repel injustice or to secure a right, but alluding is better. If your superior's absence results in severe damage to the work, then it is obligatory for you to inform the authorities responsible for him. Your fast is valid, and you must seek forgiveness and repent if your lie was without a legitimate religious justification.