Crystal structure of poly[diaqua-μ ₃-(5-(3,5-dicarboxy-2,4,6-trimethylbenzyl)-2,4,6-trimethylisophthalato)-κ ⁶O,O′:O″,O‴:O‴′,O‴″) terbium(III)-monohydrate], C₂₃H₂₈TbO₁₂