Dependency ansi_term is Unmaintained

[purew]

Describe the bug

Running cargo-deny flags grpcio since one of the dependencies are marked as unmaintained.

The output looks like

6 │ ansi_term 0.12.1 registry+https://github.com/rust-lang/crates.io-index
  │ ---------------------------------------------------------------------- unmaintained advisory detected
  │
  = ID: RUSTSEC-2021-0139
  = Advisory: https://rustsec.org/advisories/RUSTSEC-2021-0139
  = The maintainer has advised that this crate is deprecated and will not receive any maintenance.

    The crate does not seem to have much dependencies and may or may not be ok to use as-is.

    Last release seems to have been three years ago.

    ## Possible Alternative(s)

     The below list has not been vetted in any way and may or may not contain alternatives;

     - [ansiterm](https://crates.io/crates/ansiterm)
     - [anstyle](https://github.com/epage/anstyle)
     - [console](https://crates.io/crates/console)
     - [nu-ansi-term](https://crates.io/crates/nu-ansi-term)
     - [owo-colors](https://crates.io/crates/owo-colors)
     - [stylish](https://crates.io/crates/stylish)
     - [yansi](https://crates.io/crates/yansi)

    ## Dependency Specific Migration(s)

     - [structopt, clap2](https://github.com/clap-rs/clap/discussions/4172)
  = Announcement: https://github.com/ogham/rust-ansi-term/issues/72
  = Solution: No safe upgrade is available!
  = ansi_term v0.12.1
    └── clap v2.34.0
        └── bindgen v0.59.2
            └── (build) grpcio-sys v0.13.0+1.56.2-patched
                └── grpcio v0.13.0

in which you can see that grpcio-sys depends on bindgen 0.59.2 which depends on clap 2.34 which in turn depends on the offending ansi_term 0.12.

To Reproduce
Run cargo-deny as described in https://github.com/EmbarkStudios/cargo-deny?tab=readme-ov-file#usage

Expected behavior
There should be no vulnerabilities or advisories flagged in the grpcio codebase.

System information

• CPU architecture: x86-64
• Distribution and kernel version: Archlinux 6.8.7-arch1-2
• SELinux on?: Don't know
• Any other system details we should know?:

Additional context
Add any other context about the problem here.

[BusyJay]

Should be fixed by #648.