Update start.py

start.py

@@ -1,3 +1,6 @@
 import subprocess
+import os
 
-subprocess.run("app.py", shell=True)
+app_file = "app.py"
+app_full_path = os.path.join(os.path.dirname(__file__), app_file)
+subprocess.run(app_full_path, shell=True)