The Taliban are not a uniformed military force, the uniformed military force of Afghanistan is the ANA. The Taliban also are not Private Military Contractors so they are not protected under the modern revision of the Geneva Conventions.
No the Taliban are what is classified as Mercenaries.
"Under Article 47 of Protocol I (Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts) it is stated in the first sentence "A mercenary shall not have the right to be a combatant or a prisoner of war".
Killing a Mercenary is not a crime as they are not recognized as being a Combatants protected by the Geneva Conventions nor are they protected as Civilians.
That distinction would be for a tribunal to decide. Before that point, they should have been given the full protection of the Convention.