fix: delete temporary dir used for docker build (#4178)

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Delete the temporary directory used for building Docker images.

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Leaving the temporary directory leads to wasted disk space.

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internal/pipe/docker/docker.go

@@ -157,6 +157,7 @@ func process(ctx *context.Context, docker config.Docker, artifacts []*artifact.A
 	if err != nil {
 		return fmt.Errorf("failed to create temporary dir: %w", err)
 	}
+	defer os.RemoveAll(tmp)
 
 	images, err := processImageTemplates(ctx, docker)
 	if err != nil {