Automatically resolves outdated curl

[kachick]

Problem

For example

a74c117
#163

It is much annoy even if using bot for bumping base image. #137

How

• Replace curl with ubuntu bundled tool. However nix installer isn't recommended this way. wget? python? perl? awk?
• Also bump curl with renovatebot
  • Add apt datasource renovatebot/renovate#3722
• Just relax curl version such as written in https://docs.docker.jp/engine/articles/dockerfile_best-practice.html