Update rebar.config

[redgreat]

change deps git method to https, for docker build needn't set private_key. thanks.

[javiergarea]

Thank you for your contribution! LGTM 🚀 Nevertheless, the CI pipelines fail so we need some additional changes:

1. We should update both the ci.yml and docs.yml to remove the ssh-agent action.
2. Both the ndto and rebar3_ndto have its dependencies declared using the ssh protocol so they may be also updated to avoid transitive ssh private key dependencies.

I can work on 2., would you mind doing 1.? I have no rights on your branch so I cannot update your PR. @redgreat

[redgreat]

Thank you for your contribution! LGTM 🚀 Nevertheless, the CI pipelines fail so we need some additional changes:

1. We should update both the [`ci.yml`](https://github.com/nomasystems/erf/blob/develop/.github/workflows/ci.yml) and [`docs.yml`](https://github.com/nomasystems/erf/blob/develop/.github/workflows/docs.yml) to remove the `ssh-agent` action.

2. Both the `ndto` and `rebar3_ndto` have its dependencies declared using the `ssh` protocol so they may be also updated to avoid transitive ssh private key dependencies.

I can work on 2., would you mind doing 1.? I have no rights on your branch so I cannot update your PR. @redgreat

Thank you very much for reminding me to use the ssh-agent action to solve the private_key issue. I will use this method to address future GitHub clone permission problems. To avoid more cumbersome authentication, I will modify these two files in the erf repository right away.

[redgreat]

I'm sorry, the action still didn't pass. It seems to be caused by the multi-layer dependencies of libraries like ndto that prevented rebar clean from succeeding. However, my issue has been resolved, so I'll close this PR.

[javiergarea]

It is my fault, I had no time to migrate the protocol for transitive dependencies (i.e., ndto and rebar_ndto). I'll ping you when I find the time to do it so we can merge this. @redgreat

[javiergarea]

fixed in #65