Update Dockerfile

Dockerfile

@@ -1,6 +1,8 @@
 FROM python:3.11-slim
 WORKDIR /app
 COPY requirements.txt .
-RUN pip install --no-cache-dir -r requirements.txt
+# Upgrade pip and then install, specifying the index URL to bypass potential DNS/mirror issues.
+RUN pip install --upgrade pip && \
+    pip install --no-cache-dir --index-url https://pypi.org/simple/ -r requirements.txt
 COPY file.py .
-CMD ["python", "file.py"]
+CMD ["python", "file.py"]