Make Swift tests required

[szokeasaurusrex]

Note: this issue is blocked on #2545 being merged (and will possibly become inapplicable if we end up splitting that code into a separate crate)

[note to self] we should make this required for merging PRs. Will split off a separate issue for this

Originally posted by @szokeasaurusrex in https://github.com/getsentry/sentry-cli/pull/2545#discussion_r2144544072