Convert username to lowercase

.drone.yml

@@ -0,0 +1,2 @@
+kind: template
+load: docker.yaml

connector/github/github.go

@@ -270,7 +270,7 @@ func (c *githubConnector) HandleCallback(s connector.Scopes, r *http.Request) (i
 	identity = connector.Identity{
 		UserID:            strconv.Itoa(user.ID),
 		Username:          username,
-		PreferredUsername: user.Login,
+		PreferredUsername: strings.ToLower(user.Login),
 		Email:             user.Email,
 		EmailVerified:     true,
 	}