Docker: added curl run-time dependency.

It is needed for docker-entrypoint scripts to work.

pkg/docker/template.Dockerfile

@@ -61,7 +61,7 @@ RUN set -x \
          --shell /bin/false \
          unit \
     && apt update \
-    && apt --no-install-recommends --no-install-suggests -y install $(cat /requirements.apt) \
+    && apt --no-install-recommends --no-install-suggests -y install curl $(cat /requirements.apt) \
     && apt-get clean && rm -rf /var/lib/apt/lists/* \
     && rm -f /requirements.apt \
     && ln -sf /dev/stdout /var/log/unit.log