Fix cargo audit.

[vext01]

Crate:     scc
Version:   2.2.5
Warning:   yanked
Dependency tree:
scc 2.2.5
└── serial_test 3.2.0
    └── yksom 0.1.0

Crate:     sdd
Version:   3.0.4
Warning:   yanked
Dependency tree:
sdd 3.0.4
└── scc 2.2.5
    └── serial_test 3.2.0
        └── yksom 0.1.0

Simply ran cargo update.