Merge pull request #392 from BoostryJP/feature/unused_variable

feat: delete unused variable

Author: YoshihitoAso

config.py

@@ -195,5 +195,3 @@
 # Rotate E2E Messaging RSA Key
 ROTATE_E2E_MESSAGING_RSA_KEY_INTERVAL = int(os.environ.get("ROTATE_E2E_MESSAGING_RSA_KEY_INTERVAL")) \
     if os.environ.get("ROTATE_E2E_MESSAGING_RSA_KEY_INTERVAL") else 10
-E2E_MESSAGING_RSA_DEFAULT_PASSPHRASE = \
-    os.environ.get("ROTATE_E2E_MESSAGING_RSA_KEY_DEFAULT_PASSPHRASE") or "password"