updateSubmodules does not set core.longpaths #20

#19 added -c core.longpaths=true to clone, fetch, and the unshallow fetch, but updateSubmodules still runs submodule sync --recursive and submodule update --init --recursive --depth 1 without it:

https://github.com/git-pkgs/clone/blob/v0.7.3/ensure.go#L101-L115

so a submodule whose .git/objects/pack path exceeds 260 still fails on Windows.

Separately, Submodules() on Windows reports checked out commit X does not match gitlink Y for a fixture that works on Linux/macOS (https://github.com/alpha-omega-security/scrutineer/actions/runs/33872943042, TestDoSkillStagesEmbeddedNativeComponentIdentity). Not confirmed as the same cause; noting it here since the same scrutineer fixture surfaced both.

Hit at v0.7.3 from alpha-omega-security/scrutineer#986.