The purpose of this clinical trial is to evaluate the safety and effectiveness of a new combination therapy for patients with biliary tract cancer that cannot be removed by surgery. Participants will receive an immunotherapy drug called adebrelimab combined with two chemotherapy drugs (gemcitabine and albumin-bound paclitaxel) as their first-line treatment. This is an open-label, single-arm study, meaning all enrolled patients will receive this same combination treatment. The main goal of the study is to determine the Objective Response Rate (ORR), which measures the proportion of patients whose tumors shrink in response to the treatment. Researchers will also evaluate how long patients live without the disease getting worse (Progression-Free Survival), overall survival, quality of life, and any side effects experienced. The study plans to enroll 30 participants.