Update start.sh

start.sh

@@ -1,4 +1,5 @@
 #!/bin/bash
 
-# Start the Uvicorn server
-uvicorn app:app --host "0.0.0.0" --port "7860" --workers 1
+# The 'exec' command replaces the shell process with the uvicorn process,
+# allowing it to properly receive signals from the container platform.
+exec uvicorn app:app --host "0.0.0.0" --port "7860" --workers 1