The PR #1246 replaced the `getOctokit` method from the
`octokit-provider.ts` file with the `getOctokit` method from the
`@actions/github` package.
The octokit-provider was previously responsible for creating an Octokit
instance and setting the `baseUrl` via the `getServerApiUrl` helper
function. This function calls `getServerUrl` which reads the server url
from the `GITHUB_SERVER_URL` environment variable, which on GHES is set
to the enterprise instance.
This commit restores the previous behaviour by calling `getServerApiUrl`
in all places where an octokit instance is created.
Co-authored-by: Markus Wolf <mail@markus-wolf.de>
