Update clap-basic to use new Arg methods

[c12i]

fixes #616

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Things to check before submitting a PR

• [x] the tests are passing locally with cargo test
• [x] cookbook renders correctly in mdbook serve -o
• [x] commits are squashed into one and rebased to latest master
• [x] PR contains correct "fixes #ISSUE_ID" clause to autoclose the issue on PR merge
  • if issue does not exist consider creating it or remove the clause
• [x] spell check runs without errors ./ci/spellcheck.sh
• [x] link check runs without errors link-checker ./book
• [x] code identifiers in description are in hyperlinked backticks

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• [x] check if CI is happy with your PR

[h3nill]

@collinsmuriuki it seems to be fixed now.

Try

git commit --allow-empty -m "bump" && git push origin fix