fix: install libpq5 runtime in API prod Docker stage

psycopg2 compiled against libpq-dev in the build stage now has
its runtime dependency (libpq5) available in the prod stage.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

api/Dockerfile

@@ -12,6 +12,8 @@ RUN pip install --no-cache-dir --prefix=/install .
 
 FROM python:3.12-slim AS prod
 
+RUN apt-get update && apt-get install -y --no-install-recommends libpq5 && rm -rf /var/lib/apt/lists/*
+
 WORKDIR /app
 RUN adduser --system --group --uid 1000 app
 COPY --from=build /install /usr/local