Run gopls modernize on codebase (#34751)

Recent modernize fixes:
https://github.com/golang/tools/commits/master/gopls/internal/analysis/modernize

routers/web/repo/issue.go

@@ -212,7 +212,7 @@ func getActionIssues(ctx *context.Context) issues_model.IssueList {
 		return nil
 	}
 	issueIDs := make([]int64, 0, 10)
-	for _, stringIssueID := range strings.Split(commaSeparatedIssueIDs, ",") {
+	for stringIssueID := range strings.SplitSeq(commaSeparatedIssueIDs, ",") {
 		issueID, err := strconv.ParseInt(stringIssueID, 10, 64)
 		if err != nil {
 			ctx.ServerError("ParseInt", err)