This is a reversal of #632 which was filed in response to #631. The issue asserts that both the @unstable "timezones" (clocks) and "exit with status" (cli) features are at phase 3. To reach phase 3 these proposals would need to have gone through a WASI SG vote, after which they can be changed from @unstable to be marked @since instead. This vote was never held, and so the proposals cannot be at phase 3.

Here are the relevant sections from the phase process documentation:

3. Once the champion is ready to merge the proposal, they will submit a PR to the WASI repository (this repository) to file for a new phase 2 feature.
4. [...]
5. [...] The goal at this phase is to implement and iterate on the extension until it is ready to advance to phase 3.
6. Once the champion believes the phase 3 advancement criteria are met, they should bring it to the WASI SG for a vote.
7. Once the proposal is voted to advance to phase 3, the @unstable gate should be replaced with a @since gate containing the version of the next WASI release. [...]

On reviewing this I also discovered that we weren't tracking the unstable feature introduced in WebAssembly/wasi-http#139, which I've included in the list of tracked features as part of this PR.