include node_modules so release .zip is deployable

node_modules/@smithy/util-endpoints/dist-cjs/lib/substring.js

@@ -0,0 +1,13 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.substring = void 0;
+const substring = (input, start, stop, reverse) => {
+    if (start >= stop || input.length < stop) {
+        return null;
+    }
+    if (!reverse) {
+        return input.substring(start, stop);
+    }
+    return input.substring(input.length - stop, input.length - start);
+};
+exports.substring = substring;