我想通过 Cargo 运行一个示例，但遇到错误：
error: failed to parse manifest at `/Users/aviralsrivastava/dev/subxt/Cargo.toml`
完整的堆栈跟踪是：
error: failed to parse manifest at `/Users/aviralsrivastava/dev/subxt/Cargo.toml`
Caused by:
feature `edition2021` is required
The package requires the Cargo feature called `edition2021`, but that feature is not stabilized in this version of Cargo (1.56.0-nightly (b51439fd8 2021-08-09)).
Consider adding `cargo-features = ["edition2021"]` to the top of Cargo.toml (above the [package] table) to tell Cargo you are opting in to use this unstable feature.
See https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#edition-2021 for more information about the status …