math/jags: upgrade to 5.0.0

News at
https://martynplummer.wordpress.com/2026/08/03/whats-new-in-jags-5-0-0-part-1-initial-values/
https://martynplummer.wordpress.com/2026/08/04/whats-new-in-jags-5-0-0-part-2-reproducibility/