solana-pubkey: Building without `std` feature still pulls std

[vadorovsky]

Building any project depending on solana-pubkey without default features and without std causes the error:

error[E0463]: can't find crate for `std`
  |
  = note: the `bpfel-unknown-none` target may not support the standard library
  = note: `std` is required by `solana_atomic_u64` because it does not declare `#![no_std]`
  = help: consider building the standard library from source with `cargo build -Zbuild-std`

error: cannot resolve a prelude import

That's because solana-pubkey pulls the atomic feature of solana-address:

solana-sdk/pubkey/Cargo.toml

Line 32 in 65527ca

solana-address = { workspace = true, features = ["atomic", "decode", "error", "sanitize", "sha2", "syscalls"] }

solana-sdk/address/Cargo.toml

Line 14 in 65527ca

atomic = ["dep:solana-atomic-u64"]

Which then pulls the solana-atomic-u64 crate, which is not and cannot be no-std, because it depends on std (or parking_lot).

[joncinque]

Fixed with #388