“Section 552.321 confers upon the trial court the authority to issue a writ of mandamus in three circumstances: where a governmental body refuses to request an attorney general's decision on whether information is public; where the governmental body refuses to supply public information; and where a governing body refuses to supply information that the attorney general has determined is public information not excepted from disclosure.” Thomas v. Cornyn, 71 S.W.3d 473, 481 (Tex. App.—Austin 2002, no pet.); see Loving v. City of Houston, 282 S.W.3d 555, 561 (Tex.