Bump rust toolchain to 1.77

[timorleph]

This is necessary for the bump of derive_more to 1.0, which is also in this PR. The specific version is chosen for coherence with aleph-node.

All code changes are purely due to clippy becoming more demanding.

[github-actions[bot]]

Please make sure the following happened

• [ ] Appropriate tests created
• [ ] Infrastructure updated accordingly
• [ ] Updated existing documentation
• [ ] New documentation created
• [ ] Version bumped if breaking changes