fix - #463

Purpose

Fix CI

Changes

• Changed doc tests that depend on node to only be compiled and not run
• Remove usage of github action actions-rust-lang that sets RUSTFLAGS and other stuff. Now we just rely on rustup that is installed on the ubuntu runner
• Pin contract-testing dependencies to version that can be compiled with Rust 1.73

Checklist

• My code follows the style of this project.
• The code compiles without warnings.
• I have performed a self-review of the changes.
• I have documented my code, in particular the intent of the
  hard-to-understand areas.
• (If necessary) I have updated the CHANGELOG.