Fix list parameter parsing

[movermeyer]

What are you trying to accomplish?

✗ thor cldr:export --components Plurals --target=./data
Expected all values of '--components' to be one of Aliases, Calendars, Characters, ContextTransforms, CountryCodes, Currencies, 
CurrencyDigitsAndRounding, Delimiters, Fields, Languages, Layout, LikelySubtags, 
Lists, Metazones, NumberingSystems, Numbers, ParentLocales, PluralRules, Plurals, 
Rbnf, RbnfRoot, RegionCurrencies, RegionValidity, SegmentsRoot, Subdivisions, 
Territories, TerritoriesContainment, Timezones, Transforms, Units, Variables, 
WeekData, WindowsZones; got Plurals

Broke in thor v1.3.0, when the values of enum began being validated.
enum is expected to be Strings, but we were passing in Symbols.

rails/thor#784

What approach did you choose and why?

1. Fixed the Symbol/String confusion.
2. Removed the extra validation we were doing
3. Bumped the minimum version of Thor to 1.3.0.
   • So people aren't using an older version without the validation

What should reviewers focus on?

🤷

The impact of these changes

These list/enum parameters will work again

Testing

✗ thor cldr:export --components Plurals --target=./data

Checklist

• I have added a CHANGELOG entry for this change (or determined that it isn't needed)