z3-sys 0.13 generates bindings for the Z3 5.x series and resolves
GH_RELEASE_VERSION to 5.1.0 for the prebuilt-release path. The Windows
wrapper still pinned Z3_SYS_Z3_VERSION to 4.16.0, so a prebuilt Windows
build would fetch an archive that does not match the generated bindings.
Move the wrapper pin to 5.1.0 and update the contributor, architecture,
and skill references that still named 4.16.0.
Signed-off-by: Jim Meyer <jimeyer@nvidia.com>