Dockerfile: bump Alpine from 3.15.3 to 3.17.0

[ee7]

Links:

• https://alpinelinux.org/posts/Alpine-3.17.0-released.html
• https://alpinelinux.org/posts/Alpine-3.16.3-released.html
• https://alpinelinux.org/posts/Alpine-3.13.12-3.14.8-3.15.6-3.16.2-released.html
• https://alpinelinux.org/posts/Alpine-3.16.1-released.html
• https://alpinelinux.org/posts/Alpine-3.16.0-released.html
• https://alpinelinux.org/posts/Alpine-3.12.12-3.13.10-3.14.6-3.15.4-released.html

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Upstream: https://github.com/exercism/nim-docker-base/actions/runs/3532220910/jobs/5926311378#step:8:194

To-do:

• [x] Bump hash of nim-docker-base after merging these:
  • [x] https://github.com/exercism/nim-docker-base/pull/27
  • [x] https://github.com/exercism/nim-docker-base/pull/28
• [x] Merge https://github.com/exercism/nim-test-runner/pull/143