Update app.py

app.py

@@ -1,3 +1,8 @@
 import subprocess
 
+try:
+    subprocess.check_call(['pip', 'install', '-r', 'requirements.txt'])
+except subprocess.CalledProcessError as e:
+    print(f"An error occurred while installing packages: {e}")
+
 subprocess.run(['python', 'voicevox_engine/run.py'])