Allow diki to specify the latest version of a ruleset with the flag --ruleset-version=latest

[georgibaltiev]

What would you like to be added:
In order to perform a diki run with a specific ruleset, the --ruleset-id and --ruleset-version flags both need to be specified. However, the version flag can only accept values that explicitly target a supported version of the ruleset. An option to set the ruleset-version's value to latest could be added in the Diki configuration file, so the runs can always run with the latest available version of the ruleset.

Why is this needed:
Improve both user experience and possible automatizations.

[georgibaltiev]

/assign

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[dimityrmirchev]

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