GitHub: Deprecating Password Auth

[pdolif]

As it says in this blog post, "Password authentication to the API will be removed on November 13, 2020".

We are using this way of authentication e.g. in the GitHubAdapter of the Code Generation Service.
This needs to be updated until November 13.

[pdolif]

Update: Password auth is also used in the project management service. Needs to be updated there too.

[pdolif]

I've now already updated the project management service to use a personal access token instead of password authentication.
The corresponding commit can be found here: rwth-acis/CAE-Project-Management-Service@f9ef2f2

For the code generation service it should work similar.

[pdolif]

The code generation service is now also using a personal access token instead of password authentication.
The corresponding commit is: facaf7b

On October 28, 2020 GitHub temporarily shuts down password authentication. Then we should check if any problems occur, e.g. because we missed some code which uses password authentication.
If no problems occur, this issue can be closed.