GHA install JAGS fails - fix

[benjaminhlina]

Installing JAGS for Windows recently fails because SourceForge url redirects, therefore this chunk errors as it doesn't redirect properly to download the exe of JAGS.

If you replace it curl this will follow the redirect and have cmd download and install JAGS. See the following example in mcp.

I should note I found this solution as I ran into the same issue with JAGS not installing on Windows for GHA.

[joethorley]

OK great - I've pinned the issue.

[joethorley]

thanks @krlmlr and @benjaminhlina