fix: github reproduction link validation (#61026)
### What?
In this PR #60988, I think (please correct me if I'm wrong) it was meant
to block GitHub reproduction links like `https://github.com/username` &
`https://github.com`. However, the last regex `github.com` will block
all the github.com links
### Why?
So that people can use a GithHb repo as reproduction link
### How?
Fix the regex, from `github.com` to `github.com$`
Co-authored-by: Steven <steven@ceriously.com>
