fix potential writing of chart files even if testing with no actual chart

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Jan Braje <12571346+janluak@users.noreply.github.com>

pkg/action/bump.go

@@ -134,10 +134,12 @@ func (b *Bump) Run(bumpType string, chartpath string) (string, error) {
 	b.chart.Metadata.Version = newVersion
 
 	// Save the updated chart to disk (this will update Chart.yaml)
+	if chartpath != "" {
 		err = util.SaveChartfile(filepath.Join(chartpath, "Chart.yaml"), b.chart.Metadata)
 		if err != nil {
 			return "", fmt.Errorf("failed to save updated chart: %w", err)
 		}
+	}
 
 	return newVersion, nil
 }