Merge pull request #73 from Automattic/fix/deprecated-var-format

Fix: Address deprecated variable format

Author: rinatkhaziev

jsconcat.php

@@ -151,7 +151,7 @@ function do_items( $handles = false, $group = false ) {
 				if ( isset( $js_array['paths'] ) && count( $js_array['paths'] ) > 1) {
 					$paths = array_map( function( $url ) { return ABSPATH . $url; }, $js_array['paths'] );
 					$mtime = max( array_map( 'filemtime', $paths ) );
-					$path_str = implode( ',', $js_array['paths'] ) . "?m=${mtime}j";
+					$path_str = implode( ',', $js_array['paths'] ) . "?m={$mtime}j";
 
 					if ( $this->allow_gzip_compression ) {
 						$path_64 = base64_encode( gzcompress( $path_str ) );