update app.py

app.py

@@ -6,6 +6,12 @@ import signal
 import subprocess
 import atexit
 
+try:
+    import flash_attn
+except ImportError:
+    os.system("pip install flash-attn==2.5.9.post1")
+    import flash_attn
+
 
 def kill_processes_by_cmd_substring(cmd_substring):
     # execute `ps -ef` and obtain its output