Feature request: Pass SSH key for private git dependencies

[lcmgh]

When building my Rust projects I normal add a step to setup a SSH key before executing cargo. Otherwise cargo is not able to authorize itself when private git dependencies are configured.

Adding such a step prior the rust build action still makes the build not working.

# Add SSH keys for internal Git dependencies
- name: Install SSH key
  uses: shimataro/ssh-key-action@v2
  with:
    key: ${{ secrets.GIT_DEPENDENCIES }}
    name: GIT_DEPENDENCIES
    known_hosts: unnecessary
    config: |
      Host some-git-env.com
        User git
        HostName  some-git-env.com
        IdentityFile ~/.ssh/GIT_DEPENDENCIES
        IdentitiesOnly yes
    if_key_exists: replace