Remove newline from download sbom output (sigstore#1732)

fmt.Fprintln inserts a newline that isn't in the original payload. This
frustrates the process of comparing the sha256sum of the output to the
original.

Signed-off-by: Rob Best <robertbest89@gmail.com>

cmd/cosign/cli/download/sbom.go

@@ -62,7 +62,7 @@ func SBOMCmd(ctx context.Context, regOpts options.RegistryOptions, imageRef stri
 	}
 
 	sboms = append(sboms, string(sbom))
-	fmt.Fprintln(out, string(sbom))
+	fmt.Fprint(out, string(sbom))
 
 	return sboms, nil
 }