Please add support for checkouting external repositories

[mwestphal]

External repositories are not supported, eg:

- name: Checkout OCCT
  uses: actions/checkout@v2
  with:
    repository: https://git.dev.opencascade.org/repos/occt.git 
    submodules: 'true'
    path: './dependencies/occt'
    ref: V7_5_1

Does not work at all

[mwestphal]

mentioned multiple times here: #24

[Merinorus]

Hello,

I have a similar problem: my GitHub instance is self-hosted (github.mycompany.com) and I try to checkout a repo on GitHub (github.com).

I could not find any solution in discussion #24. They talk about mixing public and private repo but they are all hosted on github.com.

The only way I could bypass this was by doing a bash command git checkout.