Don't flatten row array before passing to Hash#[]

Fixes #154

lib/sqlite3/resultset.rb

@@ -86,7 +86,7 @@ def next_hash
  row = @stmt.step
  return nil if @stmt.done?
 
- Hash[*@stmt.columns.zip(row).flatten]
+ Hash[@stmt.columns.zip(row)]
  end
  end