fix: replace WriteString(fmt.Sprintf()) with fmt.Fprintf()

Replace sb.WriteString(fmt.Sprintf(...)) with fmt.Fprintf(&sb, ...) to
follow staticcheck QF1012 recommendation. This is more efficient as it
avoids creating an intermediate string.

Signed-off-by: kimsm28 <sm28.kim@samsung.com>

pkg/chart/common/util/jsonschema.go

@@ -82,7 +82,7 @@ func ValidateAgainstSchema(ch chart.Charter, values map[string]interface{}) erro
 		slog.Debug("chart name", "chart-name", chrt.Name())
 		err := ValidateAgainstSingleSchema(values, chrt.Schema())
 		if err != nil {
-			sb.WriteString(fmt.Sprintf("%s:\n", chrt.Name()))
+			fmt.Fprintf(&sb, "%s:\n", chrt.Name())
 			sb.WriteString(err.Error())
 		}
 	}