fix(ci): add riscv64 sources list explicitly for cross-rs

[vados-cosmonic]

This commit adds a hack to fix riscv64 cross builds which were missing libssl-dev packages on Ubuntu. While the package is present, attempting to install via the normal route seems to fail, and the existing package is not properly resolved.

By more explicitly adding riscv64 noble as a source, the libssl-dev:riscv64 package is properly picked up and used during the build.

This fix is admittedly fragile, but we are depending on the edge tag for cross-rs, which is inherently unstable (and likely caused this issue in the first place). Unfortunately the last non-edge release is from years ago.

Alternatively a solution I'm open to is pinning the edge release, but this may also change out from under us given that the intermediate/past shas do not seem to be retained upstream.

[mkatychev]

LGTM,
maybe for now we can add a trigger that (for now) runs on PRs that modify the cross compilation:
https://github.com/bytecodealliance/wasm-pkg-tools/blob/main/.github/workflows/publish-binaries.yml#L3-L7

on:
  pull_request:
    branches: ["**"]
    paths: 
    - "Cross.toml"
    - ".github/workflows/publish-binaries.yml"

and we can detect if we're in a PR by excluding main and tagged stuff:

if: ${{ github.ref != 'refs/heads/main' && !startsWith( github.ref, 'refs/tags/v' ) }}
run: do my tests --here