Update Dependencies, Clippy Pedantic, Rustfmt

• Update Rust Edition to 2021
• Bump dependencies:
  • proc-macro2 1.0.27 -> 1.0.86
  • syn 1.0.72 -> 2.0.72
  • quote 1.0.9 -> 1.0.36
  • thiserror 1.0.24 -> 1.0.63
  • mockall 0.9.1 -> 0.13.0
  • pretty_assertions 0.7.2 -> 1.4.0
    • Initially wasn't being used
    • But added it to tests
  • log 0.4.14 -> 0.4.22
  • trybuild 1.0.42 -> 1.0.97
• Remove unused dependencies
  • log only used as Dev Dependency
  • anyhow wasn't being used at all
• Run cargo fmt
  • Make rustfmt skip should_generate_fmt_body_for_empty_enum_data as the added , would cause the test to fail
• Update Rust images in gitlab-ci.yaml
  • rust:buster -> rust:1
• Remove proc-macro-error as it is unmaintained
  • Resolves RUSTSEC-2024-0370