rustc 1.53.0 build fails

[cteodor]

Distributor ID: Ubuntu
Description: Ubuntu 20.04.3 LTS
Release: 20.04
Codename: focal
rustc 1.53.0
cargo 1.53.0
Linux u20 5.4.0-99-generic #112-Ubuntu SMP Wed Feb 2 17:13:12 UTC 2022 aarch64 aarch64 aarch64 GNU/Linux

ubuntu@u20:~/code/fennec.upstream$ cargo build --release
error: failed to parse manifest at /home/ubuntu/code/fennec.upstream/Cargo.toml
Caused by:
feature edition2021 is required
consider adding cargo-features = ["edition2021"] to the manifest

Once added, I get another error:
Compiling digest v0.9.0
error[E0658]: arbitrary expressions in key-value attributes are unstable
--> /home/ubuntu/.cargo/registry/src/github.com-1ecc6299db9ec823/clap-3.0.10/src/lib.rs:8:39
|
8 | #![cfg_attr(feature = "derive", doc = include_str!("../README.md"))]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: see issue #78835 rust-lang/rust#78835 for more information

Compiling block-buffer v0.9.0
error: aborting due to previous error

For more information about this error, try rustc --explain E0658.
error: could not compile clap

Sorry, don't know enough rust for a PR :-)

[AbdulRhmanAlfaifi]

Hi,
Try updating the stable toolchain by running:

rustup update stable

Then compile again