Optimize Dockerfile to reduce image size

Implement best practices for package management to minimize unnecessary
data in Docker image. Remove APT cache after installation and prevent
pip from creating cache files. These changes result in a smaller and
more efficient Docker image.

Dockerfile

@@ -13,8 +13,9 @@ RUN apt-get update \
       wkhtmltopdf \
       texlive \
       build-essential python3-dev python3-pip python3-setuptools python3-wheel python3-cffi libcairo2 libpango-1.0-0 libpangocairo-1.0-0 libgdk-pixbuf2.0-0 libffi-dev shared-mime-info \
+ && rm -rf /var/lib/apt/lists/* \
  # https://stackoverflow.com/questions/75608323/how-do-i-solve-error-externally-managed-environment-every-time-i-use-pip-3
- && pip3 install --break-system-packages weasyprint \
+ && pip3 install --no-cache-dir --break-system-packages weasyprint \
  && pandoc --version
 
 COPY --from=builder /usr/local/cargo/bin/md-to-pdf /usr/local/bin/md-to-pdf