Tweak dependencies

[thompson-tomo]

Restrict TFM's which System.Collection is added for to reduce dependency graph

Closes #368

[doghappy]

Thanks for you PR, but I don't know why need to change, could you please leave extra infos to explain it?

[thompson-tomo]

when a library is compiled for a particular framework ie Net 6 a number of dependencies are provided by the framework hence the developer/publisher is not needing to include them in their release for those frameworks. In this case System.Collections is bundled in to the Framework starting with Net core 5 i think hence when compiling for a newer framework ie Net 6 that explicit dependency is not needed. This is why i have placed a condition so that the package is only included when it is actually needed due to the framework not providing it.

[doghappy]

Hi @thompson-tomo thanks for your advice, may I ask how to check if a package included in target framework or not

[thompson-tomo]

hi @doghappy the easiest way i have found is adding the additional Target frameworks to the project, then expanding the dependencies in the project tree and checking what is included.

As you can see in the picture above System.Collections is included in net 6

[doghappy]

I think we can remove both dependencies:

1. System.Collections
2. System.Net.Http

[doghappy]

reverted lot of code. and removed those 2 dependencies.

[thompson-tomo]

Handled via https://github.com/doghappy/socket.io-client-csharp/commit/cc4c7f1c25de142c8c1aae5d35ebeeb3cf1ff8c0