Cover force_mpo in simple update test

[Yue-Zhengyuan]

This PR removes an error that will never be raised.

PEPSKit.jl/src/algorithms/time_evolution/simpleupdate.jl

Lines 143 to 148 in cb2c179

	elseif length(sites) == 2
	(d, r, c), = _nn_bondrev(sites..., (Nr, Nc))
	if alg.bipartite
	length(sites) > 2 && error("Multi-site MPO gates are not compatible with bipartite states.")
	r > 1 && continue
	end

As length(sites) == 2, the error will not be raised and is redundant.

It also updated the finite-T SU test with transverse field Ising model to test force_mpo = true, i.e. applying a nearest neighbor 2-site gate as an MPO (instead of a rank-4 TensorMap) on an iPEPO.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
src/algorithms/time_evolution/simpleupdate.jl	95.12% <100.00%> (-0.08%)	⬇️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[leburgel]

I'll merge as is. The example test failure should be fixed by #353, and the gradient test timeout will require more work to sort out.