Upgrade halibut to 8.1.1591

[LukeButters]

Background

Adds:

• Concurrent collections in Dotnet are not as safe as they seem Halibut#688
• Reduce the number of calls made to Redis when the RPC is fast. Halibut#686
• Dont create ConcurrentBag within CancelOnDisposeCancellationToken unless required Halibut#685
• Don't call RegisterType twice for each RPC and with the redis queue it was 4 times! Halibut#684
• Fixes a bug in the PortForwarder in which it would not respect the port to listen on. Halibut#683
• Add observer for secure connection info Halibut#677

None of these changes impact Tentacle, they are mostly non functional changes for the Redis PRQ. The last PR adds an opt in change which does not impact Tentacle.

How to review this PR

Quality ✔️

Pre-requisites

• I have read How we use GitHub Issues for help deciding when and where it's appropriate to make an issue.
• I have considered informing or consulting the right people, according to the ownership map.
• I have considered appropriate testing for my change.

[rhysparry]

✅ I took the liberty of updating the title and then back again.

[rhysparry]

✅ LGTM