Assorted ggplot syntax changes

[VisruthSK]

With the somewhat recent release of a new ggplot2 version (4.0.0), some more arguments have been deprecated and should be adjusted. I found the following in test logs:

  ── Warning ('test-mcmc-distributions.R:93:3'): mcmc_violin returns a ggplot object ──
  The `draw_quantiles` argument of `geom_violin()` is deprecated as of ggplot2
  4.0.0.
  ℹ Please use the `quantiles.linetype` argument instead.

  ── Warning ('test-mcmc-traces.R:140:3'): mcmc_rank_overlay renders correctly ───
  Using `size` aesthetic for lines was deprecated in ggplot2 3.4.0.
  ℹ Please use `linewidth` instead.

   ── Warning ('test-ppc-discrete.R:19:3'): ppc_bars & ppc_bars_grouped return a ggplot object ──
  The `fatten` argument of `geom_pointrange()` is deprecated as of ggplot2 4.0.0.
  ℹ Please use the `size` aesthetic instead.

Though perhaps this issue should be tackled when bayesplot bumps its ggplot2 dependency to 4.0.0 or newer

[jgabry]

Thanks. The size -> linewidth is one I've tried to fix already but I probably missed a few. If you find cases that I've missed we can change those now since it's been deprecated since ggplot2 v3.4.0.