@iarna/toml strigify() adds underscores as a thousands separator

[dsolanorush]

See known issue here: iarna/iarna-toml#34

In short, when parsing numeric values over 4 digits @iarna/toml stringify method is adding an underscore character as the thousands separator. Example: 4000 becomes 4_000, which causes the generated netlify.toml to have invalid values for things like port numbers.

Is it possible to add some cleanup processing to remove underscores for numeric values?