Add GPL notices to vendored pulpcore modules - #45

Error: You need at least one "Resolves|Fixes: <issue link>" line.

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: gsactions/commit-message-checker@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/