Libertarians don't always agree on this issue. Some Libertarians are afraid that government money will corrupt private schools. Other Libertarians think that anything to reduce the monopoly power of public schools would be an improvement.
Regardless of your view on school vouchers, it's obvious that the Democrats and Republicans in the Texas legislature are completely beholden to the powerful education-industrial complex. They should reduce state spending on education, and they should reduce the power of local public school districts to tax and spend -- but don't hold your breath.
Libertarian legislators would work to get government out of education, and return it to the private sector where it belongs.