added Github teams for the core team
minor #4002 added Github teams for the core team (fabpot)

This PR was merged into the 2.3 branch.

Discussion
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added Github teams for the core team

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | no
| Applies to    | all
| Fixed tickets | n/a

Commits
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9e1f05e added Github teams for the core team