Weekly `cargo update` of primary dependencies

[obi1kenobi]

Automation to keep dependencies in the primary Cargo.lock current.

The following is the output from cargo update:

     Locking 6 packages to latest compatible versions
    Updating cc v1.0.99 -> v1.0.100
    Updating httparse v1.9.3 -> v1.9.4
    Updating lazy_static v1.4.0 -> v1.5.0
    Updating miniz_oxide v0.7.3 -> v0.7.4
    Updating proc-macro2 v1.0.85 -> v1.0.86
    Updating syn v2.0.66 -> v2.0.68
note: pass `--verbose` to see 150 unchanged dependencies behind latest