func GetPullRequestsFromGitHub(labels []string, repo string) ([]PRInfo, error) {
	pulls, err := getPullRequestsForLabels(labelsToURL(labels), repo)
	if err != nil {
		return nil, err
	}
	prInfos := []PRInfo{}
	for _, pull := range pulls {
		prInfo, err := getPullRequestHeadAndBase(pull)
		if err != nil {
			return nil, err
		}
		prInfos = append(prInfos, prInfo)
	}
	return prInfos, nil
}
GetPullRequestsFromGitHub fetches every pull requests in the provided repo that have the
given set of labels. It then returns each pull request's head SHA.
The format for repo is: "{USERNAME}/{REPO_NAME}", i.e "vitessio/vitess".
package git
import (
	"net/url"
)