ci: remove specific version from mlugg/setup-zig (uses build.zig.zon then)

.github/workflows/gen_bindings.yml

@@ -130,9 +130,6 @@ jobs:
         with:
           repository: floooh/sokol-zig
       - uses: mlugg/setup-zig@v2
-        with:
-          # NOTE: version can also come from build.zig.zon
-          version: master
       - uses: actions/download-artifact@main
         with:
           name: ignore-me-zig