fixed typo

lib/index.js

@@ -39,7 +39,7 @@ var Worker = function () {
 
 			var portIndex = debugVars.findIndex(function (debugArg) {
 				//get index of debug port specifier
-				return (/^--(debug|inspect)(-brk)?=\d*/.test(debugArg)
+				return (/^--(debug|inspect)(-brk)?\d*/.test(debugArg)
 				);
 			});