reorder commands because curl is not included with base image

docker/Dockerfile

@@ -2,7 +2,6 @@ FROM debian:stretch
 
 WORKDIR /explain
 
-RUN curl -L cpanmin.us | perl - -n Mojolicious
 ENV DEBIAN_FRONTEND=noninteractive
 RUN apt-get update && \
     apt-get install -y libmojolicious-perl \
@@ -16,7 +15,11 @@ RUN apt-get update && \
                 libjson-perl \
                 libclone-perl \
                 libtest-deep-perl \
-                libtest-exception-perl
+                libtest-exception-perl \
+                curl \
+                build-essential
+
+RUN curl -L cpanmin.us | perl - -n Mojolicious
 
 RUN cpan install Pg::Explain
 COPY lib/ ./lib/