`test/trimming/Project.toml`: Remove stale JLLWrappers dep (#59739)
`Libdl`, `Sockets`, and `Test` are non-upgradeable stdlibs that live in
the JuliaLang/julia source tree, so I didn't include compat entries for
them.
`Zstd_jll` is vendored under `test/trimming/Zstd_jll`, and is included
via `[sources]`, so I don't think we need a compat entry for that
either.
A compat entry for `JSON` was added in #59738.
So that just leaves `JLLWrappers`.