Add a default constructor to llvm::SuccIterator (gcc15) - #24

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@755da8c3cf115ac066823e79a1e1788f8940201b, actions/github-script@d556feaca394842dc55e4734bf3bb9f685482fa0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/