ci: suppress the typescript idempotency test for the github description

[om singhal (Om-singhaI)]

The typescript idempotency test against the github description started failing for every pull request once the description was refreshed. It is the generation crash from #7803, which is still open: error generating the client: Function deserializeIntoWithPath not found in namespace ApiSdk.models. I reproduced it on main at d5f667d with no other changes, so it is the description plus the generator, not any one branch.

Integration is already suppressed for typescript on this description, but idempotency is not, so it blocks the merge queue and every open pull request. This adds the matching IdempotencySuppressions entry pointing at #7803, the same shape the notion description uses for its sibling issue. Generation for typescript cannot be idempotent while it crashes, so nothing is lost by skipping it until #7803 is fixed.

Related: #7803

[github-actions]

Thanks for opening this pull request! Please add a changelog entry under ## [Unreleased] in CHANGELOG.md, before the first released version section, so users can see what changed. Add bug fixes under ### Changed and new features under ### Added.

[Vincent Biret (baywet)]

Thanks for the contribution!

I had copilot put together a fix in #8107

Closing