Dockerfile: Add jq dependency

[eskultety]

Although not strictly a direct dependency, it's a convenient tool to have in the image to construct input JSONs for our CLI from within Bash. The total install size is ~1MB so nothing tragically affecting the resulting image size.

Maintainers will complete the following section

• Commit messages are descriptive enough
• Code coverage from testing does not decrease and new code is covered
• Docs updated (if applicable)
• Docs links in the code are still valid (if docs were updated)

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