Use python_package_name for the nbextension data file

Author: jtpio

{{cookiecutter.github_project_name}}/setup.py

@@ -47,7 +47,7 @@
 
 
 data_files_spec = [
-    ('share/jupyter/nbextensions/{{ cookiecutter.npm_package_name }}', '{{ cookiecutter.python_package_name }}/nbextension', '**'),
+    ('share/jupyter/nbextensions/{{ cookiecutter.python_package_name }}', '{{ cookiecutter.python_package_name }}/nbextension', '**'),
     ('share/jupyter/labextensions/{{ cookiecutter.npm_package_name }}', '{{ cookiecutter.python_package_name }}/labextension', '**'),
     ('share/jupyter/labextensions/{{ cookiecutter.npm_package_name }}', '.', 'install.json'),
     ('etc/jupyter/nbconfig/notebook.d', '.', '{{ cookiecutter.npm_package_name }}.json'),