Enzyme tests fail on main with 4 threads since OhMyThreads 0.8.8 #71

Since OhMyThreads 0.8.8 (released 2026-10-20), the "Julia 1 - 4 threads" jobs fail on main on Linux, macOS and Windows: three tests in test/enzyme.jl (reverse, forward and batched, lines 70, 93 and 98) throw a CallingConventionMismatchError in the Enzyme rule for run_chunks. The last green run of those jobs on main (#57) resolved OhMyThreads 0.8.7; every run since #59 has 0.8.8, e.g. run 39855089242 (#67). Jobs with 1 thread, and Julia 1.10 with 4 threads, pass.

Locally (Julia 1.12, 4 threads) the full suite passes with OhMyThreads pinned to 0.8.7 and fails these three tests with 0.8.8, on main and on every open PR based on it, so the failures in PR CI are not caused by the PRs.

JuliaFolds2/OhMyThreads.jl#177 (open) fixes it: tforeach stops passing outputtype = Nothing through keyword arguments, after which the tests pass with it on main. Until it is released, CI could pin OhMyThreads = "=0.8.7" in the test environment. This is the kind of breakage #30 anticipated from the internals the schedulers override.