Fix for new versions of magic_enum + cleanup

[Xphalnos]

Since this commit Neargye/magic_enum#374, the latest version of magic_enum requires changes in externals/CMakeLists.txt.
I took the opportunity to put the dependencies back in alphabetical order.

[abouvier]

The real fix is to use #include <magic_enum/magic_enum.hpp> instead of #include <magic_enum.hpp>, and exclude the current release with find_package(magic_enum 0.9.7 CONFIG).

[Xphalnos]

The real fix is to use #include <magic_enum/magic_enum.hpp> instead of #include <magic_enum.hpp>, and exclude the current release with find_package(magic_enum 0.9.7 CONFIG).

However, the latest version is 0.9.6.

[abouvier]

However, the latest version is 0.9.6.

That's why if you update the submodule and use an unreleased commit, then you need to require the next version, because the current one will not work with the change.