feat: add authentication

Now enabled authentication by anyone with a password to be defined in
the environment variables on HF. This enables going public with the app
rather than restricting it to HF organisation members only.

.gitignore

@@ -1,3 +1,4 @@
-venv
+venv/
 .env
-output.xlsx
+output.xlsx
+.gradio/

app.py

@@ -122,4 +122,4 @@ demo = gr.Interface(
     description=INSTRUCTIONS 
     )
 
-demo.launch()
+demo.launch(share=True, auth=(os.getenv('APP_USERNAME'), os.getenv('APP_PASSWORD')))