Updating System.Threading.Tasks.Extensions to 4.5.4

[JeffAshton]

Fix for issue #1107

[stakx]

Thanks. I'd like to wait a little and see if they push another release of that library in the next few days; increasing the build number might have been a mistake that they're possibly going to fix. If they won't, I'll merge this.

[JeffAshton]

@stakx, so this strong version bump did not happen recently. v4.5.3 was released on 7/9/2019, and v4.5.4 early 2020.

Up until now it's merely been an inconvenience. Not many of the standard libraries depend on this package. But with the release of net 5, consumers of this library's dependency System.Runtime.CompilerServices.Unsafe have been upgraded. For example, System.Collections.Immutable has a dependency chain back to the next strong version of System.Runtime.CompilerServices.Unsafe.

Do you have a sense of how long you want to wait? I'm also surprised they didn't release a 5.0.0, but it looks like everything that was going to get updated had a few months of previews and RCs, but System.Threading.Tasks.Extensions has been quiet.

[stakx]

I was under the impression that this was a relatively recent change since we only just got a report about it now; but if it's been that way for a while, there's probably no point in waiting.

[JeffAshton]

I was under the impression that this was a relatively recent change since we only just got a report about it now; but if it's been that way for a while, there's probably no point in waiting.

I'm surprised it never got updated. Some packages above it did:

Microsoft.Bcl.AsyncInterfaces (5.0.0)
  -> System.Threading.Tasks.Extensions (4.5.4)
      -> System.Runtime.CompilerServices.Unsafe (4.5.3)

And there is a v5.0.0 of System.Runtime.CompilerServices.Unsafe, but System.Threading.Tasks.Extensions and System.Memory haven't been updated yet to consume it.

I think there is value in having a version of Moq that points at v4.5.4 of System.Threading.Tasks.Extensions, even if short lived, to help bridge this net5.0 gap. Given examples like the one above and this one:

System.Collections.Immutable (5.0.0)
  -> System.Memory (4.5.4)
      -> System.Runtime.CompilerServices.Unsafe (4.5.3)

[stakx]

Almost good to go. Could you please also add a changelog entry at the top of CHANGELOG.md:

The format is loosely based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).


+## Unreleased
+
+#### Changed
+
+* Upgraded `System.Threading.Tasks.Extensions` dependency to version 4.5.4 (@JeffAshton, #1108)
+
+
 ## 4.15.1 (2020-11-10)

[stakx]

Let's do this! 🚀 😉

[JeffAshton]

Thanks @stakx for the quick turnaround.