[IMP] /ocabot merge: ignore skipped check suites

[hbrunn]

In OpenUpgrade, we have a workflow that is skipped most of the time because it's super resource consuming and only makes sense to be run after merge on the main branch anyways.

Without this, ocabot treats commits with skipped workflows as failed, which it shouldn't.

fixes #326

[sbidoul]

@hbrunn given you expressed a doubt in the linked issue I deployed this manually on the OCA instance.

Let me know if it works as expected, then we can merge.

[hbrunn]

@sbidoul thanks for this, back then I wrongly looked at the status API, but this is a check suite, and here the schema enum contains value skipped.

curl -v -L -H "Accept: application/vnd.github+json" -H "X-GitHub-Api-Version: 2022-11-28" -H "Authorization: Bearer XXX" https://api.github.com/repos/oca/openupgrade/commits/2da5f3f4a81b0f785ef5dbf7fc25869a6c72bf50/check-suites

then also returns

...
{
      "id": 54035733107,
      "node_id": "CS_kwDOATBvys8AAAAMlMfacw",
      "head_branch": "18.0-ocabot-merge-pr-5443-by-hbrunn-bump-nobump",
      "head_sha": "2da5f3f4a81b0f785ef5dbf7fc25869a6c72bf50",
      "status": "completed",
      "conclusion": "skipped",
      "url": "https://api.github.com/repos/OCA/OpenUpgrade/check-suites/54035733107",
      ...
}
...

as expected