Fix ignoring node_modules in findMatchingFilesWithNode

The previous ignore pattern didn't work. Due to how we use a temp folder
as the lookup path in our findMatchingFiles test, it's tricky to add a
test for ignoring the node_modules folder. There's room for improvement:

 - we need a test
 - we should probably ignore nested node_modules folders as well

If I have time, I'll come back to this soon to make it more robust.

lib/findMatchingFiles.js

@@ -39,8 +39,9 @@ function findMatchingFilesWithNode(
   validFilesRegex: string
 ): Array<string> {
   return glob.sync(`${lookupPath}/**/*.js*`, {
-    ignore: './node_modules/*',
-  }).filter((filePath: string): bool => new RegExp(validFilesRegex, 'i').test(filePath));
+    ignore: './node_modules/**/*',
+  }).filter((filePath: string): bool =>
+    new RegExp(validFilesRegex, 'i').test(filePath));
 }
 
 /**