Drop curl from production image

Upstream can use a Bash fallback now[1] for healthchecks, so avoid
shipping unnecessary things.

[1] navapbc/template-infra@276a848

Author: doshitan

template/{{app_name}}/Dockerfile.jinja

@@ -117,7 +117,6 @@ ENV RAILS_ENV="production" \
 # Install packages needed for deployment
 RUN apt-get update -qq \
     && apt-get install -y --no-install-recommends \
-        curl \
         libvips \
         libyaml-dev \
         postgresql-client \