fix(effect)!: Change peerDependency to v4 and fix currentSpan (#24940)

Updating tests to Effect v4 and our dev dependencies of the SDK. The
`peerDependency` was updated to v4 stable as the fiber changed. We would
have needed a workaround to also support beta and rc versions, which is
IMO not worth it just for supporting a beta

Breaking because we had to change where the `currentSpan` is coming
from. With that we don't support beta versions anymore