PHP 8.2 fix

Author: dleffler

src/Server.php

@@ -218,7 +218,7 @@ protected function compile($in, $out)
 
         $v    = Version::VERSION;
         $t    = gmdate('r');
-        $css  = "/* compiled by scssphp $v on $t (${elapsed}s) */\n\n" . $css;
+        $css  = "/* compiled by scssphp $v on $t ({$elapsed}s) */\n\n" . $css;
         $etag = md5($css);
 
         file_put_contents($out, $css);