Wrong return type for os.execute

[rillig]

Environment

Luanalysis version: 1.4.0
Language level: 5.0, 5.1, 5.2, 5.3, 5.4

What are the steps to reproduce this issue?

1. local ok, kind, info = os.execute("echo")

What happens?

• The return variables kind and info are marked with 'Too many assignees, will be assigned nil.'.

What were you expecting to happen?

• The declared return type for os.execute matches the textual description in the std documentation, which suggests something like true | nil, string, number, or, when it is called without a command, bool.