Fix bar_plot log with log parameter

[mrkn]

Fixes the following error.

Failure: test_bar_plot_log[adapter: :array, backend: :plotly](PlotMethodsBarPlotTest::rendering):
  Exception raised:
  ArgumentError(<comparison of Array with Array failed>)
  /Users/mrkn/src/github.com/red-data-tools/charty/lib/charty/plotters/bar_plotter.rb:97:in `min'
  /Users/mrkn/src/github.com/red-data-tools/charty/lib/charty/plotters/bar_plotter.rb:97:in `annotate_axes'
  /Users/mrkn/src/github.com/red-data-tools/charty/lib/charty/plotters/bar_plotter.rb:53:in `render_plot'
  /Users/mrkn/src/github.com/red-data-tools/charty/lib/charty/plotters/abstract_plotter.rb:260:in `call_render_plot'
  /Users/mrkn/src/github.com/red-data-tools/charty/lib/charty/plotters/abstract_plotter.rb:254:in `render'
  /Users/mrkn/src/github.com/red-data-tools/charty/test/helper.rb:212:in `render_plot'
  /Users/mrkn/src/github.com/red-data-tools/charty/test/plot_methods/bar_plot_test.rb:236:in `block in test_bar_plot_log'