0.4.2

• bump serde from 1.0.164 to 1.0.171, which bumps syn from 2.0.18 to 2.0.25
• bump serde_json from 1.0.99 to 1.0.100
• bump toml from 0.7.5 to 0.7.6
• bump is-terminal from 0.4.8 to 0.4.9