Vulnerable to GHSA-g98v-hv3f-hcfr

[jszwedko]

Hey all,

I discovered this crate is vulnerable to GHSA-g98v-hv3f-hcfr via a dependency on atty:

atty v0.2.14
└── clap v2.34.0
    └── structopt v0.3.26
        └── prettydiff v0.6.5 (/private/tmp/prettydiff)

atty seems to be unmaintained. clap has swapped out its dependency in clap-rs/clap#4249 but this crate depends on an old version via structopt, which itself is deprecated in-lieu of newer versions of clap.

I recognize this is probably pretty low priority, but has there been any thought to migrate to clap to get rid of the dependency on structopt?

Thank you!