Change temporary file permissions to 666

Set permissions of the temporary file to 666 before replacing.
ComfyUI could be used in a shared environment and the restricted permissions introduced by this temporary file creation makes it so that workflows and other files saved through this endpoint are inaccessible by others.

app/user_manager.py

@@ -383,6 +383,7 @@ class UserManager():
                 try:
                     with os.fdopen(fd, "wb") as f:
                         f.write(body)
+                    os.chmod(tmp_path, 0o666)
                     os.replace(tmp_path, path)
                 except:
                     os.unlink(tmp_path)