Add missing comma (#649)

a missing comma does not allow the build of the Javascript file related to the collapsible menu
diff --git a/sphinx_airflow_theme/setup.py b/sphinx_airflow_theme/setup.py
index d77f724..16bf2ca 100644
--- a/sphinx_airflow_theme/setup.py
+++ b/sphinx_airflow_theme/setup.py
@@ -53,7 +53,7 @@
         'static/_gen/css/*.css',
         'static/_gen/js/*.js',
         'static/css/*.css',
-        'static/css/fonts/*.*'
+        'static/css/fonts/*.*',
         'static/js/*.js',
     ]},
     include_package_data=True,