Update core

[dandavison]

Update core to temporalio/sdk-core@8691fed

[cretz]

May have to upgrade tonic and tonic build (probably just a cargo update to update all deps in the lock would do it, probably don't need toml change)

[cretz]

@dandavison - I am a little concerned here with temporalio/sdk-core#789 and initialize workflow. It appears that it's more than a name change, it is also an order change. From the PR description:

it might require some changes to langs that are using StartWorkflow as a synonym for "do first iteration of the event loop"? If such changes are needed, they should be the ones described here: #606 (.NET may need an equivalent item) as none of these problems exist if all jobs are all read and applied to state first, before doing any iterating of the event loop.

I think we are saved by the fact that we reorder events ourselves in Python. I can't think of any non-signal/non-update/non-update-random-seed event that ever came before start in Core before that PR was created, so I think we're ok. But may be worth making sure we take a close look and confirm.

[dandavison]

I agree. I think this PR should be the first PR post-release, rather than the last PR pre-release.

[cretz]

I agree. I think this PR should be the first PR post-release, rather than the last PR pre-release.

👍 It would have been nice to get temporalio/sdk-core#818 and temporalio/sdk-core#815 and some others in this release, but I understand that reviewing this core change may take longer than we're wanting for some pure Python changes pending release.

[Sushisource]

My intention was that this upgrade should also include the changes to avoid applying jobs in different sets and thus match the behavior mentioned in #606

Having all the SDKs work the same way in that regard will be a long term win I think, and is in general just a bit simpler to think about.

[cretz]

(added #671 as being closed by this)