Install the xmlsec1 binary package

Dockerfile

@@ -17,7 +17,7 @@ FROM python:3-slim
 RUN apt-get update \
  && apt-get install -y --no-install-recommends \
       zlib1g libfreetype6 libjpeg62-turbo libopenjp2-7 libtiff5 liblcms2-2 \
-      libpq5 libmariadb3 libxmlsec1 \
+      libpq5 libmariadb3 libxmlsec1 xmlsec1 \
  && rm -rf /var/cache/apt \
  && mkdir /app
 WORKDIR /app