Update Rust toolchain to 1.73

[syrusakbary]

We should be normally 1-2 versions behind than the official version.

I got an error when trying to compile Wasmer as another crate was failing compilation. This fixes it

[syrusakbary]

The two failing tests are flaky, nothing to do with this PR

[ayys]

This broke the schema validation CI on registry with error

cargo fmt --all -- --check
error: 'cargo-fmt' is not installed for the toolchain '1.73-x86_64-unknown-linux-gnu'
To install, run `rustup component add rustfmt --toolchain 1.73-x86_64-unknown-linux-gnu`

fix was simple though, just updated the toolchain being installed as part of the CI

      - name: Install Rust
        uses: dtolnay/rust-toolchain@stable
        with:
-          toolchain: "1.70"
+          toolchain: "1.73"
          components: rustfmt, clippy