Update GitHub OAuth callback when Auth PR is merged

[dpordomingo]

Once the PR refactoring Authentication is merged and deployed, the GitHub OAuth callback must be changed to
https://code-annotation-staging.srcd.run/auth

The callback change and the release MUST be coordinated:

• The release must not be done till the person in charge of changing it is ready to proceed.
• The OAuth callback must not be changed till the release has been deployed.

[dpordomingo]

@bzz can you change it whenever we need it? or should we ask any other person?

[bzz]

@dpordomingo This can be done only by GH org admin :/

Before asking anybody for this, could you please remind what is the problem we are trying to solve by URL change? I'm trying to understand why /oauth-callbackstring would not work any more for this application.

[dpordomingo]

I just followed @smacker recommendations. I understand that /auth is more clean from the user perspective, but I can change it if you see technical or organizative problems.

[bzz]

To be honest, although I agree, name would become a bit confusing that way, I think it would be much easier to keep an old URL for now in #142

[dpordomingo]

given the prev comment, this requirement won't be done