Update toml dependency to 0.6

[cardoso]

Opened a new PR to fix the commits ( cc @itowlson )

0.6 brings full TOML 1.0 compliance and several fixes.

Only had to adapt for a small breaking change:

de::from_slice and ser::to_vec were removed, instead use from_str and to_string and convert with bytes manually

https://github.com/toml-rs/toml/blob/main/crates/toml/CHANGELOG.md#060---2023-01-23

Also a few new features which could help with parsing and editing spin.toml

Signed-off-by: Matheus Cardoso [email protected]

[itowlson]

LGTM, thanks!