Fix `MatchData#values_at` method for a range arguments

Before:
    /(.)(\d+).(\d+)/.match("$10.99").values_at(1..3)
    # => [["$", "10", "99"]]
After:
    /(.)(\d+).(\d+)/.match("$10.99").values_at(1..3)
    # => ["$", "10", "99"]
Add spec for `MatchData#values_at` with a range arguments