[collapsible_headings] bugfix typo in exporter_inliner

Author: jcb91

src/jupyter_contrib_nbextensions/nbconvert_support/exporter_inliner.py

@@ -40,7 +40,7 @@ def default_config(self):
         contrib_templates_dir = templates_directory()
 
         template_path = c.TemplateExporter.setdefault('template_path', [])
-        if templates_directory not in template_path:
+        if contrib_templates_dir not in template_path:
             template_path.append(contrib_templates_dir)
 
         return c