Revert "Update .gitlab-ci.yml"

This reverts commit 946169df1490bd4090a91658b726e389a0f096cd

app/app.py

+import sys 
+sys.path.append("/home/jovyan")
+
+import argparse
+import logging
+
+from dash import Dash
+
+from layout import layout
+from callbacks import register_callbacks
+
+logging.basicConfig(level=logging.INFO)
+
+
+# get the correct port from proxy
+parser = argparse.ArgumentParser()
+parser.add_argument("--port", type=int)
+args = parser.parse_args()
+port: int = args.port
+
+if not port:
+    raise ValueError(f"Port of proxy server for Dash not found in {args}.")
+else: 
+    logging.debug(f"Dash app running on port {port}.")
+
+# define Dash app
+app = Dash(
+    name=__name__, 
+    requests_pathname_prefix="/dash/"
+)
+
+# define layout
+app.layout = layout
+
+# register all callback functions
+register_callbacks(app=app)
+
+# Run Dash app in the notebook
+app.run(
+    jupyter_mode="jupyterlab", 
+    port=port, 
+    host="localhost",
+    debug=True
+)