verus-lang/verus-mode.el

AI Summary: The task is to update the Verus-mode Emacs plugin to conditionally handle literal strings in `Cargo.toml` files. This involves detecting the version of the `emacs-toml` library; if it's outdated, the plugin should provide a warning and fallback to the older string handling method; otherwise, the redundant code for handling older `emacs-toml` versions should be removed.