Add graphql path when creating client

[gerardsegarra]

Fix 862

After investigating for a while, I found that the problem is that shurcooL/githubv4 expects a graphql url.

Just adding the graphql path to the URL parameter doesn't work (as that same url is used to pull the repo), but just by appending /api/graphql to the s.URL when initiating the client, fixes it.

Based on official documentation, the enterprise url for GraphQL is https://<HOST>/api/graphql.

Additional Information

Tradeoff

Potential improvement

Tests are missing for all the custom URLs.

[olblak]

Thanks for looking into this.
I don't have access to a GitHub enterprise so my knowledge is purely theorical

Could I ask you to use the standard url library to do a clean url join
https://pkg.go.dev/net/url@go1.19beta1#JoinPath

something like

graphqlURL , err := url.JoinPath(s.URL, "/api/graphql")
if err != nil { 
    return nil, err
}
g.client = githubv4.NewEnterpriseClient(graphqlURL, httpClient)

[gerardsegarra]

Done :D
Thank you for being so quick reviewing this.

[olblak]

Done :D Thank you for being so quick reviewing this.

Thanks for fixing this part, if all tests are green, I can cut a release