Validate option series contract fields - #2

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/upload-artifact@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Files in the 'vignettes' directory but no files in 'inst/doc':

'loadNamespace' or 'requireNamespace' call not declared from: ‘gamlss.util’

Cannot process vignettes

Files in the 'vignettes' directory but no files in 'inst/doc':

'loadNamespace' or 'requireNamespace' call not declared from: ‘gamlss.util’