fix: use errors.New instead of fmt.Errorf for static string

Replace fmt.Errorf with errors.New for better performance as suggested
by perfsprint linter.

Author: bimakw

routers/api/v1/repo/issue.go

@@ -88,7 +88,7 @@ func buildSearchIssuesRepoIDs(ctx *context.APIContext) ([]int64, bool, error) {
 	}
 	if ctx.FormString("team") != "" {
 		if ctx.FormString("owner") == "" {
-			return nil, false, fmt.Errorf("owner organisation is required for filtering on team")
+			return nil, false, errors.New("owner organisation is required for filtering on team")
 		}
 		team, err := organization.GetTeam(ctx, opts.OwnerID, ctx.FormString("team"))
 		if err != nil {