libsoundio-sys does not build under newer cmake

[Emily-TTG]

Trying to build https://github.com/OpenGMK/OpenGMK, but this package fails to build as the libsoundio cmakelists' cmake_minimum_required is too old -- leading to the following build error:

CMake Error at CMakeLists.txt:1 (cmake_minimum_required):
    Compatibility with CMake < 3.5 has been removed from CMake.

    Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
    to tell CMake that the project requires at least <min> but has been updated
    to work with policies introduced by <max> or earlier.

    Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway.

Please consider bumping up the minimum to 3.11 as <=3.10 is deprecated at trunk cmake.

[Adamcake]

That was already done in #5, OpenGMK's dependency is outdated though.

https://github.com/OpenGMK/OpenGMK/blob/master/Cargo.lock#L626

Lists the commit prior to that PR being merged

[Emily-TTG]

Would it not be better to bump the already inlined source? Since it's just operating in whatever minimum version mode happens to ship with your system cmake as-is. Taking a brief look I don't see any cmake policy changes that should affect the project.