build: omit contributors section in case of empty array

Author: Planeshifter

lib/node_modules/@stdlib/_tools/changelog/generate/lib/format_contributors.js

@@ -100,7 +100,11 @@ function formatContributor( contributor ) {
 */
 function formatContributors( commits ) {
 	var contributors = extractContributors( commits );
-	var out = sectionStart( 'contributors' );
+	var out;
+	if ( contributors.length === 0 ) {
+		return '';
+	}
+	out = sectionStart( 'contributors' );
 	out += heading( 'Contributors', 3 );
 	if ( contributors.length === 1 ) {
 		out += 'A total of 1 person contributed to this release. Thank you to this contributor:\n\n';