fixed conversion of enc key

modeling.py

@@ -25,7 +25,11 @@ def load_db():
         with open(file_path, 'rb') as f:
             encrypted_data = f.read()
 
-        cipher = Fernet(st.session_state['encryption_key'])
+        encryption_key = st.session_state['encryption_key']
+        if isinstance(encryption_key, str):
+            encryption_key = encryption_key.encode('utf-8')
+
+        cipher = Fernet(encryption_key)
         decrypted_df = cipher.decrypt(encrypted_data)
         st.session_state['db'] = pickle.loads(decrypted_df)