fix: ckb-hash feature ckb-contract is invalid

[EthanYuan]

What problem does this PR solve?

Problem Summary:

Due to a Rust issue, the features = "ckb-contract" in ckb-hash crate Cargo.toml below did not actually work as expected：

[target.'cfg(not(any(target_arch = "wasm32", features = "ckb-contract")))'.dependencies]
blake2b = { package = "blake2b-rs", version = "0.2" }

[target.'cfg(any(target_arch = "wasm32", features = "ckb-contract"))'.dependencies]
blake2b = { package = "blake2b-ref", version = "0.2.0" }

This will result in the following two CI failures of the PR refactor: Replace ckb-standalone-types with ckb-gen-types for the ckb-std CI:

cargo build --target=riscv64imac-unknown-none-elf --no-default-features --features=ckb-types,allocator

cargo build --verbose --target=riscv64imac-unknown-none-elf --features=build-with-clang

What is changed and how it works?

What's Changed:

1. Implemented a workaround to bypass the issue

[features]
default = ["blake2b"]
ckb-contract = ["blake2b-ref"] # This feature is used for CKB contract development

[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
blake2b = { package = "blake2b-rs", version = "0.2", optional = true }

[target.'cfg(target_arch = "wasm32")'.dependencies]
blake2b = { package = "blake2b-ref", version = "0.3", optional = true }

[dependencies]
blake2b-ref = { version = "0.3", optional = true }

2. update blake2b-ref version to 0.3.

Related changes

• PR to update owner/repo:
• Need to cherry-pick to the release branch

Check List

Tests

Manual test: make the CI tests of ckb-std pass：

• rust
• build-with-clang

Release note

None: Exclude this PR from the release note.

[EthanYuan]

I accidentally deleted the branch before merging, and I have now restored the branch. @doitian