change review request access from AccessModeRead to AccessModeWrite

routers/repo/issue.go

@@ -1390,7 +1390,7 @@ func isLegalReviewRequest(reviewer, doer *models.User, isAdd bool, issue *models
 
 	var pemResult bool
 	if isAdd {
-		pemResult = permReviewer.CanAccessAny(models.AccessModeRead, models.UnitTypePullRequests)
+		pemResult = permReviewer.CanAccessAny(models.AccessModeWrite, models.UnitTypePullRequests)
 		if !pemResult {
 			return fmt.Errorf("Reviewer can't read [user_id: %d, repo_name: %s]", reviewer.ID, issue.Repo.Name)
 		}