bench: refactor to use string interpolation in buffer/from-string

PR-URL: #10500
Ref: #8647

Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>

Author: rautelaKamal

lib/node_modules/@stdlib/buffer/from-string/benchmark/benchmark.js

@@ -22,6 +22,7 @@
 
 var bench = require( '@stdlib/bench' );
 var isBuffer = require( '@stdlib/assert/is-buffer' );
+var format = require( '@stdlib/string/format' );
 var pkg = require( './../package.json' ).name;
 var string2buffer = require( './../lib' );
 
@@ -59,7 +60,7 @@ bench( pkg, function benchmark( b ) {
 	b.end();
 });
 
-bench( pkg+':encoding=utf8', function benchmark( b ) {
+bench( format( '%s:encoding=utf8', pkg ), function benchmark( b ) {
 	var values;
 	var str;
 	var out;
@@ -90,7 +91,7 @@ bench( pkg+':encoding=utf8', function benchmark( b ) {
 	b.end();
 });
 
-bench( pkg+':encoding=hex', function benchmark( b ) {
+bench( format( '%s:encoding=hex', pkg ), function benchmark( b ) {
 	var values;
 	var str;
 	var out;