You need people skills, including communication, empathy, time management, delegation etc. Technical skills are actually not necessary to lead developers, although of course it doesn't hurt if you have them. But your technical skills alone won't make you a good team lead. And most likely you won't have the time to keep them up to date, so expect them to slowly but surely get rusty, which means you will need to rely more and more on the expertise of your team members.
IMHO probably one of your greatest challenges (at least initially) will be delegation of tasks. So far you have managed to solve problems yourself, based on your tech skills. Now you will need to learn to delegate tasks to others, and trust that they will do a good job. Some of them may not be as capable as you (think you are :-), still often it is better to delegate to them, rather than trying to do everything yourself. You are now responsible for the work of the whole team, not just a specific tasks, so you must balance to have enough time for the whole team.
As a team lead, you probably need to plan ahead a lot more than you used to as a developer. And on various levels too, for a whole team, not just your own activities.
And last but not least: you most likely need to communicate a lot more than before, with a lot of other people (managers of various sorts, clients, ...) who are not developers. You need to learn to communicate with them effectively, i.e. using a language they can understand. That includes talking business speak to managers who don't understand technical jargon, i.e. focusing on the value a specific feature brings to users, and the costs, rather than the technical details of implementing it.
An absolutely recommended reading for this is Peopleware: Productive Projects and Teams (Second Edition).