fix: fix keys of action caches for contracts

[loloicci]

Description

Now, the key of action caches for contracts uses cacheFiles('Cargo.lock'). The Cargo.toml excludes contracts/*, so this key does not work well. This PR fix this to use contracts/[contract-name]/Cargo.lock.

Types of changes

• Bug fix (changes which fixes an issue)
• New feature (changes which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• ETC (build, ci, docs, perf, refactor, style, test)

Checklist

• I followed the contributing guidelines.
• I have updated the documentation accordingly. (not needed)
• I have added tests to cover my changes. (not needed)
• The PR title and commits are followed conventional commit form.

[zemyblue]

LGTM

[zemyblue]

@loloicci , The CI failure is fixed if applying the changes of #203 ?

[loloicci]

The CI failure is fixed if applying the changes of #203 ?

Yes, it is fixed in #203.