No, you are not legally required to do so. If trade unions have called a strike and employees join the call, the obligation to work is automatically suspended for the duration of the strike. If there are legal regulations in a company that is on strike concerning the employees' behavioral obligations and the obligation to sign off when leaving the workplace or the premises, these do not apply during strikes!
If you would like to notify your supervisor or colleagues nevertheless, you are welcome to do so. A post-it on your door or PC indicating “I’m at the warning strike” is fine.
Only “keyholders” need to call their supervisor before going on strike to arrange where to drop off their key or who will pick it up so that important keys are accessible while they are away.