fix: sapx benchmark - use @stdlib/string/format per RFC #8647

Author: Amansingh0807

lib/node_modules/@stdlib/blas/ext/base/ndarray/sapx/benchmark/benchmark.js

@@ -26,6 +26,7 @@ var isnanf = require( '@stdlib/math/base/assert/is-nanf' );
 var pow = require( '@stdlib/math/base/special/pow' );
 var ndarray = require( '@stdlib/ndarray/ctor' );
 var scalar2ndarray = require( '@stdlib/ndarray/from-scalar' );
+var format = require( '@stdlib/string/format' );
 var pkg = require( './../package.json' ).name;
 var sapx = require( './../lib' );
 
@@ -104,7 +105,7 @@ function main() {
 	for ( i = min; i <= max; i++ ) {
 		len = pow( 10, i );
 		f = createBenchmark( len );
-		bench( pkg+':len='+len, f );
+		bench( format( '%s:len=%d', pkg, len ), f );
 	}
 }