Updated obsoleted functions

[fgallegosalido]

The members ImGuiIO::SetClipboardTextFn and ImGuiIO::GetClipboardTextFn have been obsoleted. This pull request uses the new members in ImGuiPlatformIO.

[ChrisThrasher]

Your solution breaks compatibility with ImGui 1.89. What newer version of ImGui to you propose that ImGui-SFML 3 use?

[fgallegosalido]

It seems that the earliest that supports this is 1.91.1, so I would say that one, although I would consider using the latest (1.91.6), which is the recommended way to go.

[ChrisThrasher]

How do you acquire ImGui for use with ImGui-SFML? A local git clone? A package manager? CMake FetchContent?

[fgallegosalido]

Local git clone. I guess I should also update the CI and the CMake file

[ChrisThrasher]

How does ImGui-SFML stand to benefit from using a newer version of ImGui? Are there better features or anything else we could use?

[fgallegosalido]

This is the recommended way to go according to the developer: https://github.com/ocornut/imgui/blob/master/docs/FAQ.md#q-which-version-should-i-get.

[ChrisThrasher]

It seems that the earliest that supports this is 1.91.1, so I would say that one

I think I'm cool with this. We still haven't raised the ImGui requirement for ImGui-SFML 3 yet but I know that needs to happen at some point. This seems like a reasonable choice. Not necessarily sure I want to pick the latest ImGui release so 1.91.1 sounds good for now.