(IUCr) Synthesis, crystal structure and thermal properties of <span class="it"><i>catena</i></span>-poly[[[bis(2,3-dimethylpyrazine-<span class="symbol">κ</span><span class="it"><i>N</i></span><span class="sup"><sup>1</sup></span>)cadmium(II)]-di-<span class="symbol">μ</span>-chlorido] monohydrate]